Say I want all my Jazz, but none of my Post-Bop, which is a sub-genre of Jazz.
So, first I click Jazz, and then I click Post-Bop. Then, I just click on Post-Bop a second time, meaning “Exclude Post-Bop” – I get this, which I think is what you want:
Hopefully that helps, but let us know if not!
EDIT: I re-read and I think you’re looking for this actually.