Legal Question in Civil Litigation in California

I suppose your child could force you to take such extreme measures as an actual eviction. Depending upon your age, his behavior may even be considered elder abuse and you may need to seek a restraining order if he were to become abusive about suing to evict him from the house. Good luck. Depending on your financial circumstances you may qualify for legal aid or you may be able to get a low cost consultation through your local bar association.

Also, the 'tenant' should be made aware that any eviction proceeding on his record would seriously damage his ability to ever rent from other landlords. There are always consequences to our behavior, intended or not.

If he has paid you rent, he is correct that you must give him 30-days written notice to vacate, but you do not have to go through a formal eviction if you do not have any other lodgers in the house. Once the time given in the notice expires, his right to occupy the premises is terminated as a matter of law, and he can be removed as a trespasser under Penal Code section 602.3. If he has not paid rent, then you can immediately proceed under section 602.3.