Yep it’s possible even without mods.
Simply go to options and go to demographics. Then check on all the supernaturals and they won’t pop up in your game anymore.
However, if the game already assigned some sims as supernaturals just enable the testingcheats and shift+click on the mailbox and there should be an option to get rid of all supernaturals lifestates in the town. It doesn’t get rid of any of the sims themselves, just the lifestate.
To get rid of zombies you need this mod:
http://modthesims.info/d/486695
