But, the landlord did want his name on the agreement so he could chase after both of you if someone didn't pay the rent. You can't evict him as long as he's on the rental agreement. Perhaps he will write a new rental agreement with just your name if you explain that you want your roommate to move out. Or, if you live in a multi-unit apartment complex, maybe your landlord will let you move to another unit. Tell him that you'll probably be forced to move if he can't help you out.
Most landlords hate to lose a good tenant.
But, the bottom line is, if you can't get your roommate to move out voluntarily, you'll have to get him evicted legally. This may cost you more time and money than a move unless you can navigate the legal process yourself. Your best bet may be to tell him that either he's moving or you're moving. Otherwise, you'll probably be better off moving yourself than trying to get him evicted. Pursuing an eviction will most likely be the most expensive and most aggravating way to solve your dilemma.