This screenshot was taken after tapping the undo disable and delete option about 20 times
iClour photo library is not part of the device’s iCloud backup. It is a separate system that uses your iCloud account to sync your photos across devices. iCloud Photo Library - Apple Support
iCloud photo library is a synchronization service only. It is NOT a backup nor archive of your photos.
If you disable iCloud Photo Library, as mentioned in that warning, in 17 days the photos in iCloud will be deleted, and that deletion will be sync’d across all your devices. In other words, you will then loose all of your photos.
If you need to cease using iCloud Photo Library to free up space in your iCloud account, you first need to backup or archive your photos somewhere - your laptop or computer for example (e.g. with a Mac, transfer them to the OS X photos library), Dropbox, google or somewhere that offers archival storage separate from your iOS device.
Then delete the photos on your iOS device, which will in turn delete them from iCloud.
Or, subscribe for additional iCloud storage if you wish to keep using iCloud Photo Library.
Double tap the home button and swipe the settings up to force close it.
Also, try restarting the iPhone.
Why can’t I undo disable and delete?
