Unassigning cue list from a fader (sub)

I have a cue list assigned to a fader sub on an Ion.  I want to remove it so that I can use it as a sub.  I've tried what the manual says to do and I've also tried "deleting" the sub.  So far nothing's worked-- cue list is still there.  I'm obviously not doing something right or leaving something out.  The one thing I do know is when I hold down "Fader Controls", even before I press "Release" the sub LCD's go blank as if I'm changing fader pages.  Can someone point me in the right direction.... PLEASE?!?!

Related