Samsung Galaxy S8 - Manual (Page 179)

Settings 172
Note: When you sign in to a Google Account on your
device, Factory Reset Protection is activated. This
protects your device in the event it is lost or stolen.
For more information, see “Factory Reset Protection” on
page 12.
If you reset your device to factory default settings with
the Factory Reset Protection (FRP) feature turned
on, you must enter the user name and password
for a registered Google Account to regain access to
the device. You will not be able to access the device
without the correct credentials.
Warning: If you reset your Google Account password, it
can take 24 hours for the password reset to sync with
all devices registered to the account.
Before resetting your device:
1. Verify that the information you want to keep has
transferred to your storage area.
2. Log in to your Google Account and confirm your
user name and password.
To reset your device:
1. From a Home screen, swipe up to access Apps.
2. Tap Settings > General management > Reset >
Factory data reset.
3. Tap Reset and follow the prompts to perform the
reset.
4. When the device restarts, follow the prompts to set
up your device.