To reset the Secure Sync on your iOS device, please follow the steps below:

'Settings'> 'Secure Sync'> 'Reset Secure Sync'

The Secure Sync will be disabled on all your devices and the sync data deleted. The local data remains on your device.

You can reactivate the Secure Sync at any time to reconnect your devices. The data will be uploaded from the device you reactivate the sync  first.