Because sign-in is passwordless and code-based, your account session is simply a temporary login on the device you used. To end it, look for the Log out option on the account page and click it.
If you do not see a log out button, you can close the browser tab and clear your session there. On a shared or public computer, it is a good idea to close the browser fully when you are done.
Logging out of the account page does not affect your IPTV service on your TV or apps. It only signs you out of the web page where you view your details.