If the IRS rejects the tax return later in January you can make your changes to the tax return and re-file.
If the IRS accepts the tax return then you have to wait for the IRS to process the return and you receive the tax refund. Then you have to amend the 2020 tax return that was filed, removing the tax credit you entered on the tax return. It will take the IRS 4 months or longer to process the amended tax return.