What do you do when you hate a sim you've created?

If they aren't part of anyone's family tree I may delete them or move them to other households.

If they have family I either kill them right away (if they annoy me very much) or let them age with the other unplayed background sims in my households. I have set my limit to 150 sims in my households and whenever I approach that number I become murderous and then the sims I don't like will end up dead anyway.