If they have a written lease, you are bound to rent to them until the end of the lease--then you can remove them.If they don't have a written lease--or they had one and it expired--they were or became month-to-month tenants on an oral lease. You may give them 30 days notice terminating their tenancy. If they don't move out by the end of that period, you can file an eviction action in court to have them removed; you should be able to get instructions and sample forms from the court, either online or in-person.