Prevent others from ordering - Yes, ORDERING(!!!) - or downloading your photos!!! It's the default setting so change it!
1. Click on Photos at the very top in the black navigation bar.
2. Little Gear in the far right very top corner is your settings link for whichever aspect of G+ you are in.
3. Photo Settings > Privacy and Permissions
4. Unclick Order Prints and Download my Photos
5. Save Changes.