Logging My Account Off Another Xbox

Do you mean take your account off the other persons Xbox?

There is no way to do that unless you are at that Xbox itself.

The best thing you can do if you do not want them to have access to your account would be to change your password on your account at account.microsoft.com and that would require anytime that account tries to sign in again for the new password to be entered
and if the person does not know the new password they would not have access to your account.

If you have their xbox set as your home xbox so that they can play your games you would also want to sign into another xbox and make it as your home xbox.

Hello there,

We understand that you're experiencing an issue concerning someone else that is currently using your Microsoft account.

To sign someone off of a Microsoft account that is currently on another Xbox One console, you would simply first
change the password to the Microsoft account, and then sign into the account on your console.

Try this out, and this should further stop another user from signing into your account.

Let us know if this works, best wishes!

Changing your password will log everyone out of account prompting them asking for the new password

Change your password
here

What do you mean you're trying to sign off? Just need some clarity

As already suggested the only way to do this is by changing the password under your xbox live account.