Use the Voice Memos app - Apple Support - https://support.apple.com/HT206775
I see all it says is "save" which to me implies that you are overwriting the original. There's no "save as" as an option to create a new, edited file.
The only other way I can think of would be to completely erase the phone and restore it to the time of your last backup, if that would include the original memo.
How to erase your iPhone, iPad, or iPod touch - Apple Support
Click on this link to discover how to 'Restore your iPhone, iPad, or iPod touch from a backup' --> https://support.apple.com/HT204184
or watch this video if you're using a Mac to do this:
https://www.youtube.com/watch?v=Jbp3gGTQygg