Yes, you can downgrade with the clear and start over feature but keep in mind that he different TurboTax "flavors" handle different tax situations and their associated forms.

To clear your return and start from scratch in TurboTax as long as you haven't submitted a payment, deducted the TurboTax fee from your refund, or registered. To clear your return and start over, please follow these steps below:

• Sign in to TurboTax (if you're not already signed in).
• Click on the Take me to my return button.
• Select Tax Tools, and then select Clear & Start Over (click or tap the 3 lines in the upper-left corner if you don't see this menu).
• Then, answer Yes (in the pop-up to confirm).

Please see FAQ, for more information about downgrading: https://ttlc.intuit.com/replies/3288495