If you want to sign out of your account, you can do so by opening your account settings. You can access your settings by clicking on the cog icon next your name at the bottom left of the screen. Clicking the Sign Out button in the top right of the pop up (pictured below) will sign you out of your account on your current device.
Sign Out on All Devices
If you believe your account has been compromised and want to sign out on all devices, you can also select Sign Out on All Devices.
