As long as you have not already paid or filed, you can Clear and Start Over your return:
https://ttlc.intuit.com/replies/4248526
I have the same problem--want to clear and start over because all the numbers are wrong. I paid my fee to Turbotax but DIDN'T FILE to the IRS. It wants me to pay double my taxes! Is my return now with the IRS even though I didn't file it yet? And if not, how can I clear and start over? Thank you thank you if you can help me
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.