If his name isn't on the lease you should be able to go to the police and ask for him to be removed as by definition he is trespassing if you have not agreed he can be there. Then give him 48 hours to come an collect his stuff at an agreed time and day which the police can also attend at the same time. Depends what country you are in though on what rights you have?
Also as you are the only one on the rental agreement you can ask your landlord to change the locks. If the BF turns up and causes any trouble you can call the police. Any further trouble he gives you after this will be grounds for a restraining order (USA) or an injuction (UK) meaning he cannot come within 100 yards of you or the property or he can be immediately arrested.