NEED HELP: Unsync Gmail contacts from Address Book

I recently synced up my Gmail contacts with my friend's Mac Address Book to show him how easy it was to do, but now I want to remove all my contacts from his Address Book and I can't figure out how to do it except deleteing each one by hand. IS there a faster way to do this?

It won't let me sort by date, and it doesn't appear that the program actually stores the vCards so I can't go in there and delete those files manually. Any help would be greatly appreciated!

Thanks in advance for the help!