Sounds like two problems. Hes too full of misplaced energy/aggression, and he doesn't know his place. If your gonna keep him you need to check his ass and let him know who the alpha is and to respect you when you say to do things like cut his stupid shit out. Apparently he doesnt comprehend you could kill him with your bare hands if you wanted to and there'd be nothing he could do to stop it, you need make him realize that before hes gonna start listening. Start making his workouts brutal to the point he quits or changes his attitude, that way if he leaves its on his own terms and not being tossed out on his ass in again. Plus itll probably keep him from just going to another gym. If you want, be honest and tell him he's halfway out the door for the reasons you told us and your gonna push him and he needs to perform to prove himself to you or else he is out. Id recommend large doses of squats, burpees, and his ass constantly in the middle of a shark tank with no one going light. Make his ass too worn out to want to be a dickhead. Good luck either way.