Only the online returns can not be deleted or erased. Returns done in the Desktop program are only on your computer and can be deleted.
Are you on Windows?
Your tax return file ends in .tax2019, .tax2020, .tax2021 etc. Search your computer for it. Check the Recycle Bin or Trash. Check in One Drive, etc. it should be in your Documents then in the Turbo Tax folder. Check your backups. Also if you have multiple Windows user accounts, log into each one and do the search for the *.tax2021 data file from within each one and checking the Recycle Bin in each one.
If you don't have the main .tax file you might have one that starts with a Tilde sign ~ like "~your name.tax2021". That file is if your computer crashes or your real file gets lost or deleted or corrupt so you can restore it.
How to show the file extension in Windows
https://www.howtogeek.com/205086/beginner-how-to-make-windows-show-file-extensions/
