I can't delete my encounters and my characters have no hitpoints 

Do the encounters you want to delete have names, or are they “unnamed encounter”?  If that latter, it’s a known issue.  Give then encounters names and then you should be able to delete them.

As for player HP, the encounter builder is still in beta and does not yet pull HP and other player stats from the character sheets into the encounter builder.  The first time they had a process worked out to do that, they discovered in testing that using it to scale would probably bring the whole site down due to too many database calls.  So they had to build a whole new “simplified character data system.”  That has been done, and it looks like they are doing internal testing of pulling data.  I say that because twice now in the last several months the hosts of the weekly Dev Update has screen shared their combat tracker for other purposes (a brief game and to demo saving the combat tracker state mid-combat), and both times viewers could see HP, AC, and PP for the characters in the builder, along with a blue warning that character data was experimental and subject to change.  

So when will I be able to use the combat tracker? 

Subscribers have access to the combat tracker, as they have access to alpha features. Once it moves to beta, non subscribers will have access. My understanding is that character data must show up in the combat tracker before it is eligible to move to beta. They never give ETAs, so I don’t know how long that will take.  The other criteria for moving to beta was the ability to save the state of the combat tracker mid combat, and that was just released.