Try to come to an agreement with the roommate. If you dislike living with him enough to want to kick him out, he probably doesn't want to live with you either. Try to set a time for him to be out by. If you can agree, get it in writing, preferably with a witness.
Talk to the problem roommate. Approach the roommate when it is convenient for both of you to have a frank discussion. To soften the blow, tell him of the nice things you enjoyed about living with him. Then tell him very frankly about the issues that mean he can no longer live there. Emphasize the issues lie not with him but with a conflicting lifestyle. Do not blame the person; blame the behavior. Remain calm even if the other person is not. Come prepared with notes of specific times and dates of behavior or actions that are leading up to this conversation. If the issue escalates to court, the person with documentation always wins.