To get the google account id, please visit this page.
Click Execute button as shown in the image above.
Sign in to your email account or choose the account you wish to sign in with as shown below-
Click Allow on this screen.
A pop-up will appear in the lower right corner. Copy the id from this response.
Entering this ID under the Factory Reset Toggle button on Policy (or Template) will authorize the user to unlock the device post factory reset.
As a result, an unauthorized user cannot simply factory reset your device and use it against your permission.
On the Device
Once your device is factory reset, you will see the following screen on boot. Enter the email account corresponding to the Google Account ID entered in policy, and the device will get unlocked!
An unauthorized user cannot get through this security feature which protects the device against unauthorized factory reset.
If you forget your Google account id or cannot use this feature and have more questions, send a support ticket.