So have a difficult player that has been a pain since our group started. This was my first game that I was running and had only played in a handful as a player. The game is setup in that we play when we hang out and not have a set day to play. They have an app for making their character that lets them see stats for all races that have been set out in any of the book or home-brews that where upload to it. The chose to play a lizard-person bard that multi-classed into ranger as well. I told them to use the standard races that where in player's handbook. Nope would not do it and has hissy fits till I said fine do it. Now his GF is playing some type of angle like being cause it on the app and they are leading the party to be murder hobo range. This ends with quest derailed and things taking very long like shopping turning into full combat cause they descended to kill the blacksmith in small town who I thought was a stronger NPC but 4 on 1 does not make for good odds.

I am getting tried of this and have an asteroid/comet getting bright to the point that they can now see it in the day. Only problem is now the player has said that if his character ever dies they will just come back as the same lizard-person bard with the same stats and will not ever make another. The player is being hard in other ways as well but since we play as part of hanging out and they are  the ride for severely other friends it would be hard to just pull the one person a side and say I really do not want you at the game and just have others play. 

Had the idea that maybe thing would be different if someone else DM'ed no one else would step up and do for mouths now. Finally had the problem player run one game said they never want to again. Because we did not ask enough questions about his lizard peoples backgrounds to get the information we needed to finish the quest that he made up based off nothing and would not listen that a 23+ ac was to high for 3rd level players to go against. This was the low level bad guys not the end boss or even mid boss. Others where pointing out after the game that ended with a total party kill that maybe he and i could co DM so that he could learn things about what to ask for rolls or use a premade quest. They would not hear any of this. 

How would others deal with this person ether as a player or DM.

Some people aren't worth playing with. Period.

If you're describing them accurately, then I wouldn't play with either this problem Player or his girlfriend.

Sure - it might mean that this gaming group comes apart because of the transportation logistics, but would you prefer to find/build a new group with all sane Players, or would you prefer to continue to have this Player in your group? It's the era of the Internet, you could even run an online Discord game with the Players you like playing with, even if they've lost their transportation. And you can usually find other means of transportation.

Some people are neither worth trying to convince, nor does their way of doing things have anything constructive to teach you. In those cases: walk away.

I agree with vedexent. This is a game, not work, it’s supposed to fun, not something annoying you suffer through. Give the guy the boot. Maybe the other people will find another ride. Or maybe you start playing at their place. 

If you’re really set on sticking with the group,  you need to be more firm. It sounds kind of like he’s bullying you and you need to push back. Tell him that character is not allowed. If he throws a hissy fit tell him to stop acting like a toddler and make a new character. If he refuses, tell him a blue bolt of lightning comes from the sky and kills him, and that it’s going to keep happening. Maybe he storms out, maybe he realizes he needs to play ball. 

Where are the other two players coming down on all this?  They don't like him as a DM, but they're willing to help him murder a blacksmith as players?   It doesn't sound like any of them are really on the same page with you.  

Why don't you try to find another game where you can take things a bit more seriously, and then when you're just goofing around with your friends, maybe it'll give you some perspective on this guy's issues.  

I'd also add, if he only DMed once, and  his story was all about his lizard people, he's probably not JUST doing it to piss you off.  It seems like he might have some genuine seed of a story of his own germinating somewhere, he's just being a dick about expressing it.

I would agree with what most everyone else has posted here so far, however if you want to give this guy a chance before doing any of the above options maybe start making his characters life, not difficult per say, but certainly more interesting. Start throwing cursed items at him that punish murder hoboing, start having even stronger NPC's or hidden witnesses that report to guards making the party wanted. Basically make their murder hoboing have CONSEQUENCES, make them realise that yeah its fun but at the end of the day just killing random people is going to end up getting their character killed for sure, also maybe set a homebrew rule that if a character isnt succesfully revived then thats it, you cannot play that same character again, there must be significant changes in race and class before they are allowed to join the party again. Hope any of these ideas might help and dont seem too harsh :)

Stop playing with them and find another activity to do together.

^ - This. D&D is a game that lets people participate in fun, collaborative storytelling. One player foregoes the role of creating his own character and instead participates as the environment, the antagonist(s), and neutral/helpful NPCs. The other players do create a character, and are expected to (on one level or another) interact with and react to the environment, the antagonist(s), and neutral/helpful NPCs.

Everyone should be having fun doing so. If they're not, then D&D might not be the game for that particular group. It doesn't have to be everything to everyone; it's just a game. If playing that particular game can't make anyone happy, play something else. Or find other people to play with. D&D is not worth friendships, and it isn't something that people should wrap their entire identity around. Not being able to play D&D together with someone doesn't make you or them a bad person; it just means that in that particular instance, D&D wasn't the proper medium for spending time with your friends.

The great thing about D&D is that you can always toss that adventure and come up with something else that maybe will facilitate fun play; you can collaborate with your players when you do this, and try to fit in what kind(s) of characters they think they might want to play. That doesn't mean the setting/adventure you came up with isn't good or you should trash it. Save it for some other time, for some other group.

 I think someone alluded to maybe he has an idea in his head about his character. While I agree with cutting him loose, you could lean into the lizard folk angle. 

What if a group of adventurers came close to his tribe, and when the tribe ambush them, they are slaughtered? Plus, the group tracks down the tribe village, and slaughter the rest of them. Only a small child has the strength to flee, and lives just long enough to get work of the disaster.

It could be your first DMing experience takes a walk on the darkside.

It sounds like you're trying to play Mass Effect while they're trying to play Grand Theft Auto. Nobody's gonna have a good idea trying to play a game they think they're playing, especially when they don't know they're doing anything wrong. 

Imagine if you played GTA and were faced with realistic consequences and nuanced moral issues? That's not what you came here for-- you came here to rob hardware stores with screwdrivers and crash planes into a giant statue of a cheeseburger, so of course you're going to ignore when the game (or GM, in this analogy) keeps saying like, "that guy had a family!" Or "can we please do the mission?"

That is not to say that your players are in the right, but rather that it sounds like you guys haven't talked much about what kind of game you want to play.  Because Mass Effect (1&2) were great, but you had to be in the mood for story and RP, and not just funny violence. If that's all they're looking for, then maybe your game group should still hang out, but just play a different game together. 

Thanks all for the help. I was feeling like I was wrong as this is my first time DMing.

I was trying to let him tell the story he want with the lizard person game that he ran. But when it was clear there was no way to forward any story because he did not give any information to us and just attack after attack with no chance to rest and regain HP and spell slots.  With the enemy's having stupid high AC for the level of the other players.  The enemy have 23+ AC vs level 3 players with nothing magic or bonus items. The highest AC in the party was 15.  My barbarian had the highest chance to hit on 15 on a d20.  That was the lowest that could hit the lizard enemy's. It was just not fun for anyone else he seemed to be having a blast till I called him out in front of everyone instead of taking him aside which I had done a few time as pointers that I had learned leading before.  

I think I will run with the hidden witnesses fell that will bring everyone around that this is a world not just isolated noninteracting villages.  And at worst the comet is in my cannon. It could hit not just pass and have it be some kind sign for coming things.  Cannot have lizard people if the world they were on has ended.  

One thing I do in my campaign is limit PC race options based on geography. Can’t play a Lizard Person of there aren’t any for 1,000s of miles. Also, show them that actions have consequences. Arrest them or something. When they fight back kill them all, but them have them all come to in prison and force them to stand trial. Players hate when their characters are in prison. He will be begging for a new character before too long. 

Is your game and if they dont want to play by your rules then they simply dont have to play. Dont put up with it. As a long time DM I consider myself pretty loose when it comes to what the players want to play but in a situation like this I would not deal with it.

Kick them out of the group. 

You are the DM and you set the rules. If they can't abide by them, then you have no place for them at the table. There are plenty of people dying to get into a group.

I had a similar problem at the start of my current campaign. One of the players new to my group apparently only ever plays a Tabaxi Undying One Warlock. I informed him that none of the “Beast People” (Tabaxi, Gnolls, Aarakokra, Kenku, Lizardfolk, Kobolds, Dragonkin, etc.) live in the kingdom in which the campaign began and that he would have to wait until the party traveled to a kingdom in which they lived and then he could make his favorite character but to make something different in the meantime. He is now playing a Hobgoblin Path of the Ancestral Guardian and having a blast. 

A different “problem player” was consistently being rude to NPCs (including Bards whom they were specifically warned against being rude to as Bards are revered in that culture) and one of the more famous Bards in the land made a VERY unflattering song about the party much to the delight of an entire village AND a rival party of (NPC) adventurers. That “problem player” has asked me if he can write a less “d**k h**d” (his words) character. I told him he has to stick it out with his current character for another 2-3 sessions until a specific plot point has concluded. 

You might want to try some creative solutions before confronting your friend. You can always ask them to leave later if it doesn’t work out, but if you kick them out straight away you kinda can’t come back from that. 

I think your comet option is too heavy handed. It would get your point across in the way you want because the whole party would suffer when you only have problem with a couple of players.

You can tell the problem players that they are being a problem and why. If they can't or wont change, then you can tell them they are no longer welcome to play. If the rest of the group finds transportation a problem, play online (there a variety of means) or find a central location like a library.