Well currently you’re just deleting the most recently created User Image, rather than the User Image in question.
To delete the correct image you need to define the specific User Image you want to delete (presumably the parent group’s User Image, assuming that’s how your page is set up).
Also, bear in mind that Deleting a Thing from the database (in this case a User Image) doesn’t delete any files from your file storage (in this case an image), so if you have a PictureUploader element that is showing an image (not a User Image) then the image will remain, even after you delete the User Image.