Tap first on the Photos tab, and then on a Library of your choosing.
Then, you will see a list of all of the Art Albums that you can select to enable/disable in that library.
You have a few options here:
- You can enable/disable photos to show up by tapping on the checkbox
- You can enable/disable ALL photos in the album by tapping "Select All" or "Unselect All"
- You can delete photos within your custom art album by tapping the photo itself, and then tapping "Delete Photo"
Learn how to do this on the Control here.