I would first try logging out and logging back in to see if that resolves the issue. If it doesn’t, I’ve normally found that I have the image attached to something somewhere maybe as part of a class (background) so I suggest double checking to make sure they aren’t used somewhere.
If those don’t work, post your read-only share link How to Enable a Webflow Share Link - Webflow Tips - Forum | Webflow so we can take a look.