When you add a code to the launcher, there's a check that makes sure it exists. Once the code is there, the launcher assumes it will always be there. If I delete the code, launchers that have it will throw an error each time they launch. They still work after the error, but it's annoying, so I avoid it.
If there's a very good reason to remove a code I can basically substitute a blank pack in, but in most cases there is no reason not to leave the old one up.