You can sign out of your YouTube on your TV both with the device and remotely. Follow the steps given below for both ways:

If you have the device

In order to sign out:

• On your TV, launch the YouTube app.

• Choose from the menu on the left.

• To access the accounts page, click your profile picture.

• Click Sign Out after selecting your account from the list. 

To remove your account:

• On your TV, launch the Yt.be/activate

• Choose from the menu on the left.

• To access the accounts page, click the account icon.

• By choosing it from the list, click Remove Account.

To switch accounts:

If you notice the “Who’s Watching” screen, you can either:

• Select any account that’s signed in.

• Add a new account.

• Use guest mode.

  If you no longer have access to the device or want to log out remotely

• Open any device and navigate to https://myaccount.google.com/device-activity.

• Choose the device from which you want to log off.

• Pick Sign Out.