To access your prior year online tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/
Start the 2022 online tax return by entering some personal information then click on Tax Home on the left side of the screen.
On the Tax Home webpage -
Scroll down to the section Your tax returns & documents. Click on the Year and Click on Amend (change) 2021 return
See this TurboTax support FAQ for amending a 2021 tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-2021-return/L1gEU4G3X_US_en_US?uid=lbl29riu
A 2021 tax return can only be printed and mailed, it cannot be e-filed.