I want to e-file now instead of mailing in a printed return. How do I change this in Turbo Tax?

Go to the File tab to do so.

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

Click on Add A State to let you back into your return

I tried to add state but it is asking me to amend my return, Is there any other way to switch to file by mail? 

Click add state for 2020 and it opens and amendment 1040x 

Click on Cancel Amend on the left side of the online program screen.  Then click on Add a State to return to the 2020 original tax return.