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