Click on Images on the profile page. Select your intended image you want to delete Than where it says "In this image" click edit than then you will see People & Things in the Image you will than click remove from image than click "Save Changes to Photo Info" at the bottom of the page. When you save the changes, the photo will not appear on any profiles. Ref: https://www.wikitree.com/wiki/Help:Photos_FAQ#How_do_you_remove_or_delete_a_photo.3F
This disconnects the image from any profile, but it will still exist in the database for a short period of time so that it can be recovered. This way photos can't be maliciously or mistakenly deleted.