Legal Question in Real Estate Law in California

Re: I want to get rid of my roommate. What rights do I have?

'Roommate' covers several possible space-sharing arrangements, but it sounds as though to the landlord you are the tenant and your roommate is your subtenant. If so, in acting toward your roommate you must act like a landlord, including meeting all the requirements for eviction -- notice, etc., and you can't change the locks or remove his property until the eviction has run its legal course. If you have defined areas like separate rooms, you can lock your space.

One suggestion is asking your landlord for advice, if you get along with him/her. Another is to refer to self-help law books on landlord-tenant relations which cover the rudiments of eviction reasonably well. If you hit any snags such as thefts or refusal to leave, get a lawyer.