Thanks! I couldn't edit my comment by that time because I wasn't a member. I saw the edit option after becoming one.
I saw you asked the game to stop create evil NPC sims, as far as I cad tell, the game wants to create more diversity and drama, so there must be some sims with bad traits. You can go to game option to un-click the fill empty house so that game will stop generate more NPC to move in. But jobs that need NPC to do like gym trainer, mixologist will still be created when needed.
You can click "ctrl+shift+c" to enter the cheat "cas.fulleditmode on". This will allow you to full edit a previous-existing sim just like in CAS! Then go to the manage the world to find the sim with evil trait. You can re-assign the trait, body shape, skin color or gender...anything you want.