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.

Visit the original article here. 

 If you have not filed yet just go through the File tab and enter your Direct Deposit Info.  You don't have to start over.  If you already filed it is too late to change it.