If you do not want to auto backup photos from your iOS device to Google+, following is the process to do so:
- Open the Google+ app Google+ icon.
- Touch the menu icon .
- At the top right, touch the gear icon .
- Touch Camera and Photos.
- Touch Auto Backup.
- Switch the Auto Backup setting off.
If you turned Auto Backup on in other apps, like Google Drive, you'll need to switch it off in every app. For example, if you turned Auto Backup on in both the Google+ and the Google Drive apps, you'll need to turn it off in both apps to fully turn off Auto Backup.