When adding a new component that does not appear in Harmony's IR library to "My Devices", Harmony provides the option of creating a new IR language using an existing language as a starting point. This is a very useful feature when two different models from the same manufacturer have few or no differences between their IR languages. It is possible to override individual IR commands, i.e. "global" IR commands copied from the template, if necessary. However, I don't see a way to delete global IR commands altogether.

Why would this be useful ? The Harmony automatically generates some menus based on which commands are available in the device's IR language. In some cases, menus are being generated in response to commands that do not actually exist for a device, i.e. they were inherited from the global IR language.

As a concrete example, the global IR language for a CD player might include commands for selecting among the discs in a CD multichanger. When a new language for a single-disc CD player is created based on that of the multichanger, it inherits the IR commands for changing discs. This, in turn, causes a device menu to appear for selecting disc on the single-disc CD player.