Are you using the Online version or the Desktop program?
You can delete the amended return this way. Do the steps slowly and carefully. After you delete it then you need to manually take out the changes you made to put your return back to the original return. Or in the Desktop program you can start over in a copy of the original file if you made a copy to amend in.
How to delete an Amended return in the Online version
https://ttlc.intuit.com/community/amending/help/how-do-i-cancel-or-undo-an-amended-return-in-turbota...
In the Desktop program all you have to do is go to Forms mode and delete the 1040X. Then take the changes out.
Cancel or undo Amended return in the Desktop program
https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/cancel-undo-amended-return-tu...
