Delete photos from shared albums in iCloud
When you delete a photo or video from a shared photo album, it’s removed from the shared album on all your devices and all subscribers’ devices.
In the Photos app on your iPad, tap a shared album.
Tap Select, then tap the photos or videos you want to delete.
Tap the Delete button .
The owner of a shared album can delete photos and videos that anyone adds. Subscribers to a shared album can delete only the photos and videos they add.