log off
To sign out of one's account, as on a computer or some digital platform, such as a website. Remember to log off my computer the next time you use it, OK?
log someone off
and log someone out[for someone] to cause someone to exit from a computer system. (This exit may be recorded, or logged, automatically in the computer's memory.) Mary had to rush off to an appointment, so I logged her off.
log off
and log outto record one's exit from a computer system. (This action may be recorded, or logged, automatically in the computer's memory.) I closed my files and logged off. What time did you log out?