Check your local and state tenant laws before proceeding. Every state and/or jurisdiction has a set of laws that pertain to the rights of tenants. You need to know what they are, to avoid the risk of a lawsuit for unlawfully forcing a roommate to evacuate your apartment or house.
See if you can get help from your landlord. If your roommate's name is also on your apartment lease, he technically has equal standing with you, and only the landlord has the actual authority to evict a tenant. Getting a landlord's cooperation can be challenging. If, however, you can persuade him that your roommate refuses to pay his part of the rent; presents a danger to you and other tenants in the apartment complex; or has violated the terms of the lease agreement, the landlord may consider removing your roommate's name from the lease and evicting him.
Go to court and get an order of protection against your roommate if she has attacked you physically or threatened your life. Once a restraining order has been issued against an individual, she must stay a designated distance away from you, and can be forced to keep away from your apartment or house. This is just a short fix, though, and only enforceable for a matter of weeks. If you still feel that you are in danger, once that time period passes, you will need to go back to court to find out if you can get another order of protection against your roommate.
Make sure your roommate is properly served with a written eviction notice. This is feasible if you are the owner of the home or are subletting your apartment. An eviction notice lets a tenant know that he has a certain period of time in which to vacate your apartment or house. Most jurisdictions require a 30-day notice, although the time period could be either considerably less or more in some states. To be sure that everything is in order, from a legal standpoint, you should probably get an attorney to examine your eviction notice. Remember that you need to spell out the specific reasons you are evicting your roommate, in case he decides to protest the eviction in court.
Call the police to get their help in getting your roommate to leave, she still refuses to go after the time period stipulated on the eviction notice is exceeded. From that point, it may become a matter of criminal trespassing, and your roommate can be arrested.
Try to persuade your roommate to leave by personally appealing to him, if all other avenues have been unsuccessful. Offering options to him--such as resources for finding other living arrangements or even offering to pay part of his first month's rent in his new apartment or dwelling--might get him to better cooperate. The more accommodations you are able to make, the more willing your roommate may be to move.