cannot delete annotations

Once an image file has an annotation applied and saved, the annotation is flattened into the underlying image and cannot be removed.

At any time while in Preview with an annotation on your image, and before it is saved, you can either undo it with ⌘Z, or via the Inspector panel's right-most tool which would list the current annotations on the image. You click the annotation in that list and press delete to remove it.

Preview was in NeXTStep and after all these years, Apple has not seen fit to code it for annotation removal after it has been saved. Your alternative would be to use a real third-party image editor that supports layers and use that.

Having a slow day here. Apple's Preview application can undo saved annotations after all.

Open the image with the annotation. On the Preview File menu, select Revert To > Browse All versions… Click the up arrow on the right of the annotated image, and go back in time until the annotation disappears. Click Restore and save the document.

You would have to save a photo as a PDF first.

VikingOSX wrote:

Apple has not seen fit to code it for annotation removal after it has been saved.

That would be rather difficult for a bitmap image.

Just sorting pixels… 🙃

Well, I've played quite a bit with various AI apps to try and remove various objects from images. Sometimes you get the bear, sometimes the bear gets you. 🤔

Perhaps a magical application that subtracts pixels that are different from an original image… I hear that growl already…