Right, if you haven't mailed in your taxes yet, you can simply go back in and make the change and reprint. When the print and mail option is selected, the program thinks you have filed, so to get around this and get back in to make changes, please see the instructions below:
How to get back into make changes online when mailing
In TurboTax Online, sign into your account.
Select Tax Home in the left menu.
Scroll down to Your tax returns & documents.
Select 2020, and then select Add a State (you're not actually adding a state, this just gets you into the right menu).
Now you can make any necessary changes.
