If you're a Vampire, you could use influence emotion: burst of anger + a couple of mean interactions, you will eventually get a chance to 'slay vampire' (you must win the fight for this to succeed). Under the friendly interaction, there's 'offer to cure vampirism' If you're a human, build some relationship with them beforehand (Get to close friend should be enough). Make a vampire cure (cost 2500) and keep it in your inventory. In case above fails, you'll have to turn them into human so that they can die in ways that mortal sims do. Maybe luring them into sun will do the trick but that's only limit to a certain fedgling vampires.Īpparently they can be burnt to death.
You can't straight off 'kill' one, they are pretty resistant with their power, at least to my knowledge, death by emotion wouldn't work.