I filed a amend because TurboTax instructed in an email to file a 2020 amend fed return for the $10,200 Unemployment tax break. The IRS says not to. How do I cancel it?

If you started amending TurboTax Online accident and would like to cancel:

1. Open your return if it isn't already open.
2. In the left menu select Cancel Amend.
3. Select Yes, I want to cancel my amended return and Continue.

How do I cancel or undo an amended return in TurboTax Online?

In most cases, you will NOT have to amend your federal income tax return to get back money if you filed before the federal unemployment exemption became law. The IRS is sending refunds, based on this adjustment, beginning in May and will continue issuing refunds through the summer. 

EXCEPTION: Some taxpayers may be eligible for certain income-based tax credits not claimed on their original return, such as the Earned Income Tax Credit for their qualifying children. If so, they should file an amended tax return if the amendment makes them eligible for additional benefits.

IRS begins correcting tax returns for unemployment compensation income exclusion; periodic payments to be made May through summer

States
Some states may require you to file an amended return. See Do I need to amend my state return to update my unemployment?