If you have NOT filed the tax return then use this procedure to return to the tax return -
To access your current or prior year online tax returns sign onto the TurboTax website with the User ID you used to create the account - https://myturbotax.intuit.com/
When you sign onto your online account and land on the Tax Home web page, scroll down and click on Add a state.
This will take you back to the 2021 online tax return.
If you have filed the tax return then the only way to change the filed tax return is to amend the return.
Before starting to amend the tax return, wait for the tax refund to be received or the taxes due to be paid and processed
See this TurboTax support FAQ for amending a state tax return - https://ttlc.intuit.com/community/amending/help/i-need-to-amend-my-state-return/00/26510