You can't directly disable Program Change inputs to the H9 (sorry – no-one has asked for this).

You could:

1) Set [RCV CH] to OFF. This would disable MIDI CC as well.

2) Set the [RCV.MAP] entries to OFF. This would be tedious if you had many PC's to consider.

Neither of these approaches are ideal – normally if you send it a PC you expect it to respond.