So would it be reasonable to recommend kill $pid as a first step and kill -9 $pid if that doesn't work? Bear in mind that this is a tutorial for beginners, so things like kill -15 $pid || kill -2 $pid || kill -1 $pid || kill -9 $pid (as another commenter suggested) aren't appropriate, but I feel like kill is too important a command to leave out completely.

On the other hand, it seems almost all the times when I've had to use kill it's because the process has already refused to die by more normal means and I doubt it'd respond to a non-9 kill.