Can i delete all and start over

In TurboTax Online, you can clear and start over as long as you haven't paid or registered yet (free users are asked to register their accounts before they file).

Note: You can’t clear and start over using the mobile app. Instead, log in to your TurboTax account from a desktop or mobile browser to clear and start over.

1. Sign in to TurboTax Online and open your return by clicking the orange Take me to my return button.
2. With your screen maximized, click My Account (at the top of your screen toward the right) and select Clear & Start Over. (If on a tablet or phone, you may find the Clear & Start Over option by clicking the three parallel lines, or “hamburger”, in the top left corner.)
3. Answer Yes to Are you sure you want to clear your return?
4. After your entries have been cleared out, we'll prompt you to select a TurboTax product so you can start over from the very beginning.

I have already paid for turbo tax 2019 at Cosco.  Can i still start over?

Despite the answer above, you CANNOT delete or start over once you've paid or registered. -- not even on a desktop. 

It's very frustrating as they've made a mistake on my state return... my only option is to abandon it and go elsewhere.