how do i clear the complete form and start over?

Just start a new return. You can keep the old one and not use it or delete the old one.

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.