A FOR loop is only appropriate if you need to execute something a fixed number of times and that number is known at the start of the loop.
In all other cases you should use a WHILE loop, it will run until certain conditions (e.g. pressing a stop button ;)) are met.
Of course in this particular simple case, you could cheat and stop the FOR loop by stopping the entire VI (See image), but that's NOT the way to go, of course (There is typically other code that needs to keep running!). You should use something along the lines suggested by tbob.