There are two things to consider: Firstly you want to back up all your precious files and make sure no one else has access to them, and secondly you need to turn off the Activation Lock or
Factory Reset Protection.
As well, you'll need to disable the phone's anti-theft software, reactivation lock, and
factory reset protection.
While
the Factory Reset Protection feature is there on paper, it seems anyone can actually bypass it.
With the growing number of Android devices being stolen, Google resolved to unveil the current Android 6.0 Marshmallow with a feature known as
Factory Reset Protection.
Factory Reset Protection (FRP) Lock is the built - in security feature that comes with Android devices, allowing the users to protect their devices and information, including the screen locks, data encryption, and other files.
The latest Android security update seems to be holding true to its promise — patching
a Factory Reset Protection (FRP) bypass bug that had recently been publicized.
Samsung has a tight security to prevent bypassing of Google Account Lock also known as
Factory Reset Protection or...
The January security update for Nexus devices has already patched a recently publicized
Factory Reset Protection bypass bug that previously affected Samsung and LG devices.
Two CVE markers labeled Moderate by Google point to a way to bypass
the factory reset protection in the Android setup wizard, and these issues have been patched.
If you're relying on this feature, then that means you're handing your phone over already unlocked to someone, so it's not as if this bypass gets around your phone's main security measures like the password / pin / fingerprint or other encryption measures or
factory reset protection.
If the person who sold you the phone didn't remove their Google account before the factory reset, you might be seeing Google's
Factory Reset Protection feature asking for the seller's Google account / password.
Not exact matches
Device
Protection is one important feature that keeps the lost or stolen devices locked even if the
factory settings
reset is tried and functions only when signed in with actual Google account.
Android 5.1 brings support for multiple SIMs and cross-platform HD Voice, along with Device
Protection which ties your Android device to your Google account and prevents unwanted access to your device even if it goes through a
factory reset.
Device
Protection also works even when the phone is
reset to its
factory settings to ensure that thieves have no way of using a stolen device.
Google's Device
Protection is aimed at ensuring that even if your phone is lost or stolen, it will stay in lockdown mode until you sign in with your account info, regardless of whether the thief has
factory reset the device.
Device
Protection — Lost or stolen devices will remain locked until you sign in with your Google account, even if
reset to
factory settings.