I want my roommate out and his name is not on the lease which is monthly. I already gave him 30 day notice but he is refusing to move out. Can I get him out without just cause?
Why don't you punch his lights out and throw him out the door with a warning that if he comes back you'll break both his legs? His name's not on the lease, and I would assume none of the utility bills are in his name, so you have no written agreement. It's your word against his that he's your roommate and not a guest that you want to get rid of, that is, a trespasser. And your name, Allan Smith, IS on the lease, so you have a leg to stand on and he doesn't.
Oh wait, there's a permanent public record now on BiggerPockets that he's your roommate -- you just made the above post documenting that in your own name. Sorry! You're out of luck. Have you tried talking to him, looking at the situation from his point of view, and using your adult conflict resolution skills to reach an imperfect but workable solution?
This is why you shouldn't take on roommates unless they're on the lease.
Without a written agreement, you have to act as if you are on a month-to-month agreement and follow the laws accordingly. I would give him written notice demanding he vacate within 30 days or whatever your state requires. You could even offer some cash if he departs early ($XX for each day remaining in the month after departure).