How do you get A roommate out that's name isn't on the lease?

In California, the landlord must serve the individual a formal eviction notice which must specify the person very clearly: on the lease or not. If the "roommate" has been residing there for a period of two consecutive weeks, then they are considered, by California law to be a legal occupant, and the land lord must use the above measures to have that person removed legally. But most experienced landlords are aware that evicting only one of two or more occupants residing under the same roof, is grounds for an ugly law suit as that could be construed as prejudice (why just me and no one else)?? So landlords tend to either evict everyone or no one. Landlords can evict for a good reason, or a bad reason, but they can not evict for no reason. If the roommate(s) are not on the lease, then landlords will mention everyone on the lease, and add the phrase "anyone else who resides there now". To make sure all occupants are covered in the eviction notice. As a fellow room mate, you can only get that person out if you shared an intimate relationship, and he or she has been making terrorist threats or has been physically abusive to you, and you fear for your life, but YOU MUST be on the lease other wise the court will not grant your request for the restraining order.