The Alternative Minimum Tax Carryover for 2021 is showing around 8K. I need to change it to zero. Turbotax will not allow you to edit this figure? Any ideas?

You might be eligible for the AMT credit on this year’s taxes if you got hit with the AMT in a prior tax year because you exercised ISOs or claimed accelerated depreciation. If you're showing $8k as a Credit for AMT Paid in a Prior Year, reducing the credit amount to zero may have a negative impact on your current year refund or amount due. 

In TurboTax, to navigate to the AMT Tax Carryover amount: 

1. Select Federal from the left menu.
2. Select  Deductions & Credits from the top tab.
3. Scroll down to Estimates and Other Taxes Paid, show more and select Start/Review next to Credit for AMT Paid in Prior Year.
4. On the next page you'll be able to enter zero.