You can stop sharing an album with specific people by removing them from the subscribers list. To stop sharing a photo album entirely, you can delete it.
WARNING: When you delete a shared album, it’s immediately removed from your devices and your subscribers’ devices. If you think your subscribers might want to keep any photos or video from the album, you should alert them to save the items before you delete the shared album. Also, make sure you’ve downloaded any photos and videos that others have added to the album and that you want to keep. The photos you shared aren’t deleted from your Photos library.
In the Photos app on your Mac, click Activity below Shared Albums in the sidebar, then scroll to view changes.