How to get out of "sudo -s" command in Terminal?

Press Ctrl+D will log you out of Super User and return you to normal user status. Alternatively, you can type exit

Type exit then you will log off to normal user. Then type exit again to close the terminal or just close it with the mouse.

If you're not doing anything important in the terminal, you can actually just click Close Terminal on the Close this terminal? ("Closing the terminal will kill it") dialog box.

This will send SIGHUP to the running shell, which will then quit, just like it would if you used the exit command or Ctrl+D (also good ways).