Hmmmmmm, it does not work that way for me.
I selected my M4 (I added him to the Favorites out of an external runtime, if it does matter) and I used that button to remove him from the Favorites. It deleted my original M4 .cr2 out of my external linked poser pro runtime, really! The original .cr2 is not there anymore, but the shortcut and the thumbnail in p8's collections folder stayed. And I made sure the Favorites tab was active when I pressed the minus sign.
I have now only M4's Genitalia left in my external linked Poser Pro runtime :laugh: