I started on an old project I had done in 8.5 last night and the tracks were using the Sonitus EQ.  I wanted to delete that EQ and use the Quad-Curve EQ in the Pro Channel.  When I turned on the Quad-Curve, I had a message that told me to control+click on this button to delete the old eq.  I did it and nothing happens.  What am I doing wrong?
 

That sounds about right. Nothing is supposed to happen. Have you tried adjusting the Quad EQ after you control click? All your Sonitus setings will be gone but it will activate the PC EQ on a flat setting so you can use that instead.

When you try to use the PC EQ it will ask you (as it did) if you want to replace the pre-PC Sonitus eq.  Control-click and voila - you did it.  Now you should be able to use the quad-eq.  If you do change something on the PC you shouldn't get the replace query.  Be sure and make sure the EQ is on, too.