As long as you haven't submitted payment, deducted the TurboTax fee from your refund, or registered, you can erase your return and start from scratch in TurboTax Online.

1. Sign in and select a topic to continue your return.
2. On the next screen, from the left-side menu, select Tax Tools, and then Clear & Start Over (select the menu icon in the upper-left corner if you don't see this menu).
3. Answer Yes in the pop-up to confirm.

Alternatively, you can delete just the form that has errors, by 

1. Selecting Tax Tools,
2. Select Tools,
3. Select Delete a form,
4. Find your form and delete it.

Since you have paid for the program you cannot clear and start over from scratch ... however if you have not filed you can delete a form and/or correct any section required.