I printed my 2020 returns in March but never mailed. I do not need to file an amended return so how can I edit original as the system thinks I mailed?

If you printed the forms and never mailed them, all you have to do is mail them now, unless changes were made after you printed them. If changes were or need to be made, you can add a state as a backdoor to get into the return to reprint.

Click on Add a State to let you back into your return.

From Tax Home (the first screen you see after you sign in), scroll down to Your tax returns & documents. You may have to select Show to open the drop down.

Select 2020, and then select Add a State (you're not actually adding a state, this is just the workaround).

Then when you are ready to file you can try to switch to efile.

  https://ttlc.intuit.com/community/e-file/help/how-do-i-change-from-mail-to-e-file-in-turbotax-online/00/26985