An active terminal will quit if you tell it there's no more input.

That can be done with a quick Control+D.

If you have things running (or something already typed into a terminal input), that won't work. You'll either have exit or clear the line. Control+C will usually work for that.

Alternatively, running exit isn't much of a hardship.

Note that these will bump you out of one layer of shell. If you start this in a subshell of a subshell, logged into something over SSH, it'll take a few goes to close the window.