Your lease is not with dealer, but with the finance company. Can you not talk directly to them instead of through dealer. Ask them the lease buyout quote. Ideally, they don’t charge you sales tax. You can send them the payoff quote amount, and they should be sending you a bill of sale and original title. As soon as you get the title, sell it to a dealer who can accept such title. Search for ‘California 10 day lease buyout…’. There is a lot of information on how to avoid sales tax if you resell the car in 10 days.
EDIT - check this out - California 10 day tax exempt For lease buyout - #54 by kaz5