I want my roommates to move out because they have pets
Why don't you want to live with pets?
Because pets equate to smelly, disease and medical problems.
If you allowed them to get pets in the first place, you shouldn't go back on your word. Is this just an excuse to kick them out?
I can make all of them miserable because I'm evil.
You know, if you want them out for another reason, you should just talk to them instead of being inconsiderate by kicking them out.