Legal Question in Real Estate Law in California

Several points need to be made:

1. A legal claim to live there might arise from an oral agreement. A written agreement is not necessary. The real question is whether there is an agreement.

2. Written agreements can be enforced against a party who signed it by a party that didn't sign it. Your defense to enforcement might be that you didn't sign, but you'll get nowhere arguing that the other party or parties didn't sign. Generally speaking, at least.

3. There is, however, a possible way to get rid of someone who is just renting a room in your residence. Such arrangements often make the renter a "lodger" rather than a true tenant. Such persons have only a license to share space in your home, and when you notify them that the license is terminated, they fall into the trespasser category. You don't have to give them notices of file an unlawful detainer.

Unfortunately, without seeing the unsigned agreement or knowing other facts, I can't say with certainty that these people are lodgers or true tenants. I suggest you do some further research using a search engine or find a book that describes who is a tenant and who is a lodger. Or ask a local lawyer for a brief consultation.