Legal Question in Real Estate Law in California

You will need to begin the eviction process to remove them.

Well, I'm a lot less certain that beginning the eviction process is the right step. First, you need a determination as to whether these occupants are tenants, guests, lodgers or merely trespassers. I'd be inclined to think they are your guests, since you (apparently) are the sole owner of the house and (apparently) are letting these non-owners stay there for free. They may, however, have fallen down a notch and become mere trespassers if you've asked them to leave and they haven't.

I'd recommend having an in-person conference with a local real-estate lawyer where you can lay out all the history and facts, so he or she can decide which category they fit. I'm guessing "guest" is most likely, but the facts could point to another legal category.

If they are guests, you should notify them (preferably in writing) that they are no longer welcome and must vacate within a reasonable time. This could be anywhere from a few days to a few months, depending on factors such as how much furniture they've moved in.

If they fail to leave, they become trespassers, and at that point you can have the sheriff handle their removal......and it may be worth the money to have a professional eviction service handle all the messy details.

When they're gone, change the locks, have the place watched, and hire a contractor or two to estimate the damage done -- then consider filing a lawsuit to try to collect.

The important thing to note here is that tenants have a lot of rights, guests have far fewer, and trespassers have next to none......so find out what they are before taking action.