How to delete merged photos
Delete merge photo
Delete merge photo
Please read the following user tip and restate your question/problem in detail:
Writing an Effective Apple Support Communities Question - Apple Community
Generally if you merge two duplicates Photos keeps one, add all of the metadata of both to the one it keeps and deletes the other.
Do you what to delete the remaining photo? You'll need to find and select it and while holding down the Command key press the Delete key.
Can you give us more details?
If you have shared photos from another user on your iPhone, only this user can delete these photos:
Add and delete photos and videos in a shared album on iPhone - Apple Support
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copied from: Checklist 3: Manage content - Apple Support
How to delete merged photos