(california) How Do I Evict My Girlfriend When I Don't Own The Apartment?

Location: California

My girlfriend has been at my house for a little over two years. She never formally moved in (and I never asked or wanted her to), and doesn't spend every night here, but she's here more often than not. She doesn't pay rent (or for anything) and never has, won't work and never has, isn't in school, and won't even walk her dog. (I have to do it.) She mostly watches TV all day while looking at her phone, and has no interest in ever doing anything else. I've tried being understanding, I've tried being assertive, I've tried giving her space, I've tried planning things for her, I've tried asking her to go to therapy ... nothing works. No abuse, drama, or legal issues, just the unrelenting stress of enabling an adult child.

I'm absolutely done, and have tried to break up with her several times, but she refuses to acknowledge it and pretends nothing happened. This has been a surprisingly effective strategy to date, but I've reached a breaking point and need to get her out.

I'm not sure if she's legally considered a tenant because she only receives some of her mail here. (Her car isn't registered at this address, for example.) All her stuff *is* here, if that matters. Everything I've Googled about eviction notices seems to presume that I'm the landlord or the owner, but unfortunately I'm just a tenant, and I don't want to involve the landlord because having her here may be a violation of the lease. Do I have authority to write an eviction notice on my own, presuming it's properly served and I give her 60 days, and if so, how do I word it? I could write one even if I don't and try to bluff, but I strongly suspect she'll ignore it and force my hand, since that's been her unvarying strategy so far.

I've tried buying her out (offering her financial incentives to leave) and she's agreed, only to then ignore the deadlines and stay, so I see no options other than formally evicting her or giving notice myself, leaving, and dealing with the fallout of the landlord having to evict her.