Please see this FAQ if you use TurboTax Online:
https://ttlc.intuit.com/replies/3301384
Please see this FAQ if you are using TurboTax CD/Download:
https://ttlc.intuit.com/replies/3450510
https://ttlc.intuit.com/questions/1900608-how-do-i-delete-my-state-return-in-turbotax-online