Your return does not go to the IRS until you file it.
If you have already paid, you don't have a "Clear and Start Over" option - your best alternative will be to use the "Delete a Form" tool to remove as much of your existing tax information as possible and then revisit the interviews.
See: How do I delete forms in TurboTax Online? Start with the tax information you entered - W-2s, 1099s, 1098s, etc., and look for worksheets that include that information. After deleting these forms and worksheets, log out of the program. When you log back in, use the Delete a Form tool (List of Forms in My Return) to confirm these forms and worksheets have been removed from your return.
