Deleting Shared Albums in Photos

You are asking about "turn off shared albums", but the title of the question is "Deleting Shared albums". What do you wat to achieve? Do you want to delete your Shared albums or just turn off Shared albums temporarily? If you just turn off the iCloud Setting for Shared albums, they are not deleted. They will come back, when you enable Shared albums again, but the content will be reset to the items that are currently still in iCloud. Turning shared albums on a device off and on will essentially clear the cached contents of the shared albums on your device, but the shared albums will remain in iCloud.

On macOS 12.7 the shared albums are not using your paid iCloud storage. The shared albums are using a free separate part of iCloud storage. So turning off shared albums will only save storage on your devices, but not in iCloud. This has changed with iOS27 and macOS 27 Golden Gate. Shared albums you create now on the 27 versions are sharing the albums from your iCloud Photos Library and are using your paid iCloud+ storage. But on older system versions they are still using the free iCloud storage.

Did you already have a look at these related articles?

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Participants can choose to leave a Shared Library at any time. If you’re the organizer of a Shared Library, you can delete it. When you delete the Shared Library, all participants receive a notification and can choose to keep all of the items in the Shared Library in their Personal Library.

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copied from: Manage Photos sharing settings on Apple devices - Apple Support

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 If you plan to remove someone from a shared album, it’s a good idea to let them know in case they want to save any photos or videos from the shared album. When you remove someone, they no longer have access to the shared album and its contents.

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copied from: Add and remove people in a shared album in Photos on Mac - Apple Support