Hello. I live in New York City and I have a 20yr old son that lives with me, he pays no rent, he has no job and doesn't appear to be looking for one. I believes he smokes weed from time to time. I have a younger son at home that I feel my older son is a bad influence on. How can I throw him out of my house, he will turn 21 on August 26, 2012 .

You need to have him legally evicted.

Yes, you give him legal notice to move, if he does not, you start eviction though the court.