If
you prepared a 2015 federal return using TurboTax you could go back to your 2015 account and prepare a 2015 Ca return. You will have to pay to do so. Or you could just get the form from the state's website and prepare it by hand--make sure you have your 2015 federal return in front of you for reference. You do not say how long you lived in CA in 2015--you might only need to prepare a part-year CA return if you moved during the year.
To finish a prior year return started in TT online:https://ttlc.intuit.com/questions/2559403-how-do-i-finish-a-prior-year-return-that-i-started-in-turb
When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS and/or your state received the return.
If you want to use TurboTax to do this, do it soon. The 2015 software will be retired in a few weeks.
https://www.ftb.ca.gov/help/index.html?WT.mc_id=akContact