You can have her removed by filing an "ejectment" action; "ejectment" is basically eviction for non-tenants; or you may be able, since she was the girlfriend of a tenant, to treat her as a holdover tenant (a tenant who stayed past move out date or termination of tenancy) and remove her through an eviction proceeding. You can get her out, but *must* go through the courts--you will incur liability if you try to simply lock her out on your own, turn off her utilities, etc. A good idea, since this is not the typical (and easiest) eviction case of a regular tenant who has not paid rent is to retain a landlord-tenant attorney to help you; let the lawyer decide on which of the possible courses of action is best.