Short answer: Patch the source.
Displaying icons in all kind of DEs follows usually somer rules from freedesktop.org.
In order not to have to code each icon again and again, freedesktop defines a set of icon-names for all that widgets, actions and so on.
The purpose of this is, to get a consistent user experience and make life easier for programmers.
If the programmer chooses to use that naming-scheme, there is no more call to display a specific icon in the source anymore.
The icon will be loaded from the DesktopEnvironment from the default icon scheme (which names the file or files of that icon).
Apperently Konsole does not offer a choice not to display this icon.
So the only way left to remove it, is to patch the source of Konsole.