Using Markup in Photo and Preview in OS13.6

Select and open your Photo>Edit>Reset adjustments (located at the bottom) for the common adjustments

For "markup tools" that you used for ex. adding text—simply highlight the text added previously and delete.

Save changes.

If an image not stored in a Photos library has been annotated using Preview, & you wish to revert to the original,

open the image using Preview, then: Menu bar > File > Revert to > Browse All Versions…

Scroll back to the version required, then click on Restore: