Disabling Contacts Sync in your iPhone or iPad.
To disable contact synchronization with Exchange Server, please follow these steps.
1. Tap on Settings.
2. Tap on Mail, Contacts and Calendars.
3. Select the Exchange Account.
4. Tap ON for Contacts to turn syncing OFF.
5. A warning appears -“All Exchange Contacts will be removed from iPhone”.
6. Select “Keep on my iPhone”