If it is a PRO app, and If you did not PUBLISH after you deleted that feature, and if the "Auto Publish* feature on the SHARE screen is OFF
then you can go to the PUBLISH button (the arrow on the right of it), and you should see a “discard”.
I hope that helps.
Also, I often duplicate my apps (at least one duplicate per important feature or modification) so I can go back if I messed up. Then I will delete the oldest backups when they are no longer needed. That may not help this time, but for future reference.