If Activation Lock is enabled on the device, iCloud credentials are required to reset the device. To reactivate the device, you should provide the iCloud credentials that was used to enable the activation lock. If iCloud credentials are not available, then the Activation Lock Bypass code can be used to reactivate the device.
To reactivate the device using the Activation Lock Bypass code:
Either unenroll the device from ZCC by selecting Fully wipe the devices, resetting them to factory setting or reset the device by using Apple Configurator.
For more information, see Unenrolling Devices.
When prompted for Apple ID and password, leave the Apple ID field empty and enter the 16 digit bypass code in the password field without specifying the dashes.
NOTE:You can reactivate the device using the Activation Lock Bypass code only if Activation Lock Bypass is enabled on the device.