Quitting the Spell Catcher X application changed significantly in version 10.2.2. Do yourself a favor, make sure you're using Spell Catcher X 10.2.2 or later, and forget about all the "tips and tricks" related to quitting previous versions.
In the Spell Catcher application, choose Spell Catcher > Quit Spell Catcher (or type Command-Q).
If you see an alert about Spell Catcher being the active input source, click the default Quit button.
That's it! Unlike previous versions, there's no need to choose a keyboard from the input menu, and the Spell Catcher application will reliably "stay Quit".
To start using Spell Catcher again:
Choose Open Spell Catcher from the input menu (if Spell Catcher is still the active input source), or
Open the Spell Catcher application as you would any other.
Quitting Spell Catcher X versions 10.2.1 and earlier
Quitting the Spell Catcher application wasn't quite so straightforward prior to version 10.2.2. If you are still running one of these older versions, read on. If you're using Spell Catcher X 10.2.2 or later, the above is all you need to know.
View the FAQ for the version of Spell Catcher X and Mac OS X you're using