You cannot file only your State return in TurboTax.
The TurboTax State program is designed to pull (transfer) information from your
federal return. For this reason, TurboTax State is not sold as a standalone
tax-preparation product.
You can use TurboTax to prepare and file your federal
return without your state – but not the other way around.
See this FAQ for more details: https://ttlc.intuit.com/replies/4232481