What happens if I click "delete backup", do I still have my photos on the camera roll? I'm running out of space in iCloud, so I decided to turn off all the backups and delete them. 

What happens if I click "delete backup" at the bottom of the manage store page? 

Do I still have my photos in the camera roll?
Yes! It will only delete your backup. Not your photos that are in the camera roll.

If you delete the iCloud backup for your iOS device, iCloud stops automatically backing up the device. You can also back up your device using iTunes.