Let's just say you already have a big problem on your hands. Whatever you do now is going to be far from ideal.
For example, a man might ask his friends, "What should I do when my 15 year old son gets right up in my face and cusses me out? He's actually stronger than me."
Well, no matter what you do, it's going to be bad. The PROBLEM is not having taught your son to respect you when he was younger. Now whatever you do (ignore it, kick him out of the house, etc.) is going to be bad in some way. At this point, there's really not much you can DO the truly rectify things.