First off it is your house and not his. There need to be rules and consequences if he is going to live under your roof. Remove the computer and television if you have too. Take the door off the hinges if need be. He is not being respectful and so he needs to learn to treat you and the house with respect. Do whatever it takes to send him the message that he is not to act disrespectfully. You can lay the ground rules and if he cannot abide then he has to leave. He wil test you but if you stand your ground then he should straighten up. Good luck.