I was using a computer somewhere to login my site as admin, but forgot to logout. How can I logout my account from another computer?
I think you can just remove the relevant entries from the sessions table:
That should log the user out everywhere.
I wrote up a small drush command to do this:
Technically, this just deletes the session and doesn't do a proper logout. Those are nearly identical, though, under most circumstances.
This patch hasn't been committed, so you would need to download drush extras and apply it, or just extract the file from the patch and add it to your local commands.