If you already e-filed your California State return, you may not be able to generate Form 568 after the fact. But these instructions by GeorgeM777 are your best option.
"...when you sign back into your account, select the option to add a state. You won't actually be adding a state, but this is a "back-door way" to re-open your return in TurboTax. Adding a state is an option in the My Info section of TurboTax and can be found at the bottom of the screen where it says Other state income. Just select Edit, and pick any state in the drop-down list."
Now go to the State Tax tab. Follow the interview and look for two screens relating to Form 568: California requires that you e-file Form 568 and Creating Form 568. If you see those pages, you may be able to create Form 568 to print and mail to the state.
California requires a waiver be included with Form 568 when a taxpayer prints and mails Form 568. Here is the link to the CA website that relates to waivers: Business Entity E-File Waiver Request. Scroll down the page and select Start Waiver to get your waiver request.