For the customers to undo the changes that have been made to the images they have to click on the Reset Button displayed on the right side of the Alignment section.
After the customized image has been uploaded click on the Reset Button to reset the changes.
Select the option among Keep Original, Remove Image Background and Remove All White.
Further select the option according to your preference and click on Apply to apply the image onto the product.
This is how Reset functionality will work.