I know if I type w I can get a list of all logged in users.
I also know that killall -u USERNAME kicks all processes associated with the user USERNAME (including bash / their shell, their sshd process, etc). As far as I know this is how you're supposed to "kick a user off" your server.
However I don't know how to kick off all users. Do I have to somehow w | cut -d' ' -f1 to get a list of users (and then somehow strip off the blank line and USER field and your own username) and feed that to the -u command for killall?
Or is there a better way?