Since you didn't claim the credit on your original tax return, you will need to file an Amended U.S. Individual Income Tax Return, Form 1040-X. The IRS will not calculate the 2020 Recovery Rebate Credit for you if you did not enter any amount on your original tax return. [2020 Recovery Rebate Credit — Topic G: Correcting issues after the 2020 tax return is filed]
Since the TurboTax software will automatically remove the first $10,200 of unemployment benefits, just let it do that. Your records at the IRS should be updated with this information and you won't show up in their review as needing further adjustment.
