You can sign out of Facebook on each device one by one, or on all devices at once through your account's settings.
But, if you forgot to log out and no longer have access to the device, you can still log out of all devices at once from your Facebook's account settings.
Here's how to log out of Facebook on any device one by one, or on all devices at once.
Click "Select all", then "Log Out" to log out of devices.
Click "Log Out."
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