Legal Question in Real Estate Law in California

Probably not, assuming they are truly guests. Rent isn't always taken in cash; sometimes tenants pay in services such as remodeling, repairs, or working in your business. But just because they did some trivial chores like mowing the lawn is not enough to elevate their status from guests to tenants. As mere non-paying guests, they are a cut above trespassers, but they do not have the rights of paying tenants. You can simplt inform them, preferably in writing, that they are no longer welcome as guests and that you expect them to leave at their next reasonable opportunity. The controlling law seems to be Civil Code section 1940, which says that a tenant is a person "who hires a dwelling unit," and "hiring" implies payment of some consideration, usually money, but it could be services.