Evicting a Roommate

[Coach]

Room mate for 8 years, first 3 were girl/boy friend. Last 5 no relationship.
Has never been on rental lease of mobile home space (calif) (I own). Lives in residence about 5 days week, has other mailing address (PO Box). Sleeps in separate room, no personal contact; movies, dinners, weekends etc. Never has paid for rent, utilities etc.
I would like to have her move out but refuses stating since she has been here so long I can not evict her.

[Mr. Knowitall]

California instructions for ending a tenancy.