He is not a trespasser or squatter if he is there with permisstion of the prior owner. He is a tenant at will. You will have to go through the eviction process of serving him with written notice to move, probably a 60 Day Notice if he has been there over a year. If he doesn't move within 60 days, then you will have to start an unlawful detainer action. DO NOT use self help methods such as changing the locks or turning off the utilities to get him to move.
Answered on Jan 14th, 2016 at 1:32 PM