You will need to resign an corporate officer and Board member, as appropriate (no form, just a letter dated and signed).
You will need to transfer your stock shares to the remaining shareholder - sign the back of your stock certificate. Make sure the stock transfer ledger is updated.
You will need to file a new Statement of Information with the California Secretary of State (no filing fee if amended already filed annual statement) to remove you as officer, board of director and registered agent for service of process, as appropriate.
Remove your name from all bank accounts by all walking into the bank together.
There may be other agreements that you have executed as a surety or given a personal guarantee to such as leases, franchise agreements etc. If this holds true, you will want to speak directly with counsel.
Tamara's answer pretty well covered it. The only thing I would add is that often the principals are guarantors on the merchant credit card account, and that can be a big source of potential liability of you don't get yourself removed as a guarantor. If your restaurant takes credit cards, get in touch with the bank or other financial entity that issued your merchant account, and tell them you will be transferring your shares in the corporation, and resigning as an officer and director. Tell them you need to terminate any personal guaranty that you may have on the merchant credit card account. If you have a file on this then take a look at it to see if you are a guarantor.