As per california law, can my apartment manager show my apartment complex before i vacate?

I can't speak to California law specifically but I've rented in many different states and find this issue pretty similar everywhere. In general a landlord can show your place while you are still in it. The catch is that usually the landlord has to give you some kind of advance notice when they will be doing it-call it fair warning if you will. I'd guess that different states require slightly different time frames for how much advance warning you are allowed-weather it is hours or days. If it's a good landlord it would be in good taste to do this regardless of the law. Good communication between both parties works best for everyone. Hopefully the tenant would make an effort to tidy up in return which would help the landlord rent the place out faster. Try calling your landlord to talk to him-offer to work with him with the showings (cleaning, offering to temporarily be out, etc.) if he'd give you some amount of time's notice before showings.