Find My iPhone includes a feature called Activation Lock that is designed to prevent anyone else from using your iPhone, iPad, or iPod touch if it's ever lost or stolen.
Activation Lock is enabled automatically when you turn on Find My iPhone on a device using iOS 7 or later. (Make sure Location Services is enabled on the device)
Note: During the iOS initialization process if you enable iCloud, Find My iPhone is automatically enabled.
An end-user's Apple ID and password are required to unlock a device that has Activation Lock enabled, even if the device is wiped or factory reset, including through DFU mode.
If the user doesn't have access to the iOS device, they can sign in to www.iCloud.com or the Find My iPhone app on another iOS device, then erase the device and remove it from the device list.
Activation Lock Check: Users can enter in the serial number of the device, to check if Activation Lock is enabled or disabled.
Clear Activation Lock
To disable Activation Lock use the Clear Activation Lock command in the device details page.
This requires that the device is Supervised and iOS 7+.
If the device is not supervised and the end user is unattainable, you will need to contact Apple to discuss further steps needed to remove the activation lock. You may be required to provide a proof of purchase.
Note: If the Apple ID is changed after enrollment, the activation bypass code initially provided to the MDM by the device will be changed. In this case, the device needs to be re-enrolled so that the MDM may receive the new bypass code generated by the device. If not, the bypass code validation will fail.
Force Activation Lock On
For supervised devices running iOS 7 and higher, you can force Activation Lock to be enabled To do this:
1. Navigate to Groups & Settings ► All Settings ► Devices & Users ► Apple ► Apple iOS ► Managed Settings.
2. Select the Activation Lock setting.