How to delete all contacts off iPhone 3G at once. if you are tired of deleting contacts one by one, you can delete them at once with this way. From your iPhone 3G, go to Settings > Mail, Contacts, Calendars.> select your MobileMe account.> turn contact syncing off for over the air syncing. This will erase all contacts from your iPhone.( If this is on and you turn it off, it will remove all contacts from the iphone.
If this is off and you turn it on, it will remove any contacts from the iphone and sync what is out on your mobile me account.)

Tags: delete all contacts, iphone-3g