Give him one last ultimatum and if he doesn't sort himself out, pack his bags and when he's out of the house, get the door locks changed.
Are you sure you're not encouraging his attitude by continuing to do his laundry, tidy his room and cook his daily meals and generally let him think life owes him a living. . Withdraw all your services to show you're serious and don't feed him. When his belly starts to rumble he might start to realise you mean business. Remove any equipment like TV or computers from his bedroom too so that he can't stay there and skulk away pretending he's living on another planet.