If the photo just needs to remove it from the wrong person, then just delete the tag to that person.
In Family Tree, if a photo or document shows up on the wrong person, it means that memory contains a tag to that person. Any user can fix this problem by detaching the tag, which removes it from the wrong person’s record.
When I add a photo to the wrong person, I delete the TAG for the wrong person without bothering anyone or the photo.
Here are some "Knowledge Articles" in 'FamilySearch'
Can I delete my comments on photos, stories, documents, and audio files in Memories?
How do I change a photo to a document or a document to a photo in Memories?
Can I remove a photo, story, document, or audio file from Memories?
How do I restore memories that I deleted?
How do I permanently delete memory items?
I hope these help.
I've found you can delete a photo from a memory however it will delete the photo from all memories that it is attached to and the photo collections.
Example is a group photo that you have attached to several people in the photo. Opps and attached it to the wrong person. If you delete it it will remove it from everyone and the photo collection so you will need to rescan it.
Trying to find a way to just remove it from the wrong posting and not the collection.
@LegacyUser Any photo (or other type of memory) you upload/add to FamilySearch can be deleted. Here is a link to some instructions. You can jump "Steps" to see the steps for deleting a photo.