I'm DMing a campaign with 6 characters. 5 level 6, and 1 level 7. The level seven is a rogue, and the party keeps trying to rid him. The rogue is chaotic evil. Every time he's bored (ALL THE TIME) he leans over, shanks someone, and disappears in a puff of smoke (not literally). He's taking the assassin rogue path, so he murders several people at a time. This player is advanced, and usually thinks his way out of any situational punishment i give him. He also uses any other punishment to his own advantage. HE DROPPED A COMMONER OFF OF A CLIFF WHEN I LOWERED HIS STRENGTH BECAUSE HE WAS TOO WEAK TO HOLD HIM UP!!! I don't know what I can do to punish him. (FYI, he's a 3-year player)

Talk with him out of session and tell him he needs to stop this behavior(many since it seems to be disruptive to the rest of the party and unenjoyable for them) if that fails as he continues, then boot him from the game, if he’s really causing problems for the other plays and shows no sign of stopping then you ever right to boot him from your game 

5 options, listed in the order you should try them:

1) Talk to the player.  Tell him he's detracting from the other player's fun, and your fun, and he needs to stop.  Ask him what you can do to help him not be bored or otherwise avoid the motivation for his bad behavior, and ask why he's doing it.

2) Have the other players talk with him.  Have them make it clear it's not just bothering you the DM, but is bothering them as well and is making the campaign less fun, and they'd like to see change.  This is assuming the players feel that way, which it sounds like they do.

3) Use mechanical motivation to discourage douschebaggery. I have a "fate points" system in homebrew and houserules, and it works to great effect at my tables to discourage those with bad tendencies, perhaps it would work at your table as well.

4) If it's still going on, let the players kick the evil character from their group, which they absolutely would do, and if he refuses to leave, let them kill him, or whatever else they see fit.  If somehow he finds a way to escape, make it clear he's now an enemy of the group and an NPC, and no longer under player control.  Have him roll a new character.

5) If the new character is a rehash of the old one, or is similarly evil or disrupting, kick him from the group.  You did your part, it's just not working out, time for him to go.

I understand #5 is tough, but if done right (try these at a one per session rate, so it's Clear this is an issue which is not going away unless the behavior changes, and only move on to the next one if you don't see improvement or see improvement and then it reverts to just as bad the next week), the player will have had weeks, if not months, of warning this was coming and chances to change behavior.  I've gotten as far as 3, and that worked so well for me that I never needed to move further than that, personally, but hey, hopefully it won't even come to that point.  Good luck!  Next time just don't let people play evil characters from the get-go.

Well, firstly, I'd just want to repeat what GiantOctopodes said in that you probably should not have let him make an evil character. If everyone was going to play evil/bad characters then that's totally different. Trying to mix hero PCs with foil PCs is necessarily a recipe for success as you're finding out. All of the above suggestions that GO (formerly known as GiantOctopodes) mentions are good. If the other players are not having fun and wanting to get rid of them then that's a huge problem and deserves to be talked about. I recommend NOT in private. Have an open discussion with the table about it because it is affecting everyone having fun. If that player cannot come to a consensus with the rest of the group then, well, perhaps he/she is not a good fit for the group as a whole. It happens. I've had to kick out a best friend of mine because he was/is one of the most annoying rules lawyers to play with and it was annoying the other players and even myself as it would constantly slow down play.

Just to shift gears a little, if you do have characters doing things that are kind of shady in the world you're playing in, then make them have consequences. Evil character guy wants to shank an innocent bystander? Okay, well, now he's got knights from the city guard after him that want to arrest him for the murder of a citizen. Character actions in game do bring consequences; sometimes ones that are not that great.

Fudge damage rolls in combat and kill him 

I appreciate all your feedback!

 Thanks GiantOctcapodes, I will use these tactics. Especially the low rolls on the damage csheet416. jimmop, your reply will most likely be used, and Nobleauger, I will see if the party wants to kill him, if he doesn't change his act!

Matt Colville just put out a fantastic video on problem players. He gives the disclaimer up-front that every game is unique, and that there is no "magic bullet" solution for problem players at the table. Then he proceeds to dole out some very useful tips to DMs in the kind of situation it sounds like you're in right now.

Have an adult conversation with the player about his disruptive character. If he refuses to change his play style, uninvite him.

Trying to solve a problem with a player by punishing his character is futile at best.

Have you ever heard of the Almighty Flowchart?

First try to ask him personally to stop, explain to them the definition of chaotic evil(it's not just stab stab murder murder, it means you put your own needs above anyone else and don't truly follow laws unless doing so would be to your advantage). If he persists, work through it in-game. Have cities refuse to let him in. Give him impossible to beat run-ins with the law, like fifteen gladiators led by five champions and a warlord. Try not to kill him with these unless he exploits your caution. At the end, he is either playing a chaotic neutral or chaotic good character (or still evil if he stops murdering) or he is rolling the stats for his new character.

Quote from Sirbearingtonn >>

First try to ask him personally to stop, explain to them the definition of chaotic evil(it's not just stab stab murder murder, it means you put your own needs above anyone else and don't truly follow laws unless doing so would be to your advantage). If he persists, work through it in-game. Have cities refuse to let him in. Give him impossible to beat run-ins with the law, like fifteen gladiators led by five champions and a warlord. Try not to kill him with these unless he exploits your caution. At the end, he is either playing a chaotic neutral or chaotic good character (or still evil if he stops murdering) or he is rolling the stats for his new character.

You are right that his actions translate to chaotic evil, I never denied that. I just think he isn't playing a chaotic evil character right. He's playing the alignment more like the chaotic evil of a demon. CE is more acceptable as a charlatan who cares nothing of the losses of his victim.

It's quite clear to me he's doing it almost to taunt you. He knows very well you don't like it, but he continues anyway. In-game punishments just won't work. I suggest you consult with your other group members to make sure it really annoys them too. If it does, you can and should do the following move.

Before you start play at the beginning of a session tell him that his behavior has been ruining the campaign. Remember, the job of a dm, as well as tell the story, is to make sure everybody has fun. Currently the players aren't having much fun. Therefore, you need to give him three choices. Make a new character, one that doesn't undermine the game, let him keep playing the character without such murder, or, maybe, the only option you have is to kick him out of the group. I understand your reluctance to do something like that, it could hurt your friendship, but if no one else is having fun you don't have much of a choice. Frankly, he will probably choose option three. He is almost playing chaotic evil in real life: Not obeying your rules and not exactly caring about the annoyance it brings. Give him the option, but don't count on his continued participation.

Remind him that he is playing WITH a party this isn't some RPG game where no one is gonna punish you or hate you for your actions. He is playing with other humans. If he's a friend tell him simply to either change his character or let his Evil work for something that doesn't affect the party. Though not many are willing to play with a CE character but they can have a good story if they are played correctly. 

If he changes his character tell him to ask himself few questions before he chooses his character to pick. Why is his character going to work with the party? and why would the party welcome his character?