I want to get this guy out of my mom's house legally.?

People in hell want ice water unless your names on the lease and you're paying the rent who your mom snuggles with is up to her. If you're an adult move out if your a minor sit back and enjoy the ride because either way it is none of your business.

EDIT: MIND READING COSTS EXTRA! I answered the question that you asked you added some details in the comment and then you have the balls to chide me for not reading your mind?!?!? Those who do not know the whole question should refrain from ASKING them.

Well here's the answer If his is the only name on the lease it isn't your Mom's house (SOMETHING YOU NEGLECTED TO ADD) then ALL of you have to move when the lease is up or your Mother will have to try to qualify for a new lease herself you don't just get to keep living there.

Tell Hillary in town and has a rally down town then change the locks

You do not. Your mother would have to evict him.