Icon pull down list

Hi: being able to create custom icons is a great feature. Is there any way to delete the existing icons so only the custom ones you’ve created for a specific project show up when you go to the Change Icon pull down under document? Or do those icons come from OS X (and I’d have to get involved in OS X coding to change.) Just a minor thing, but in my current projects I’m only using my own custom icons, so it would make things easier.
Thanks. David.