My terminology might be inaccurate.
I cannot remove the Pane area above my library list, which I keep at the bottom section of the window. (I keep my Playing Now list at the top section of the wondow.)
The best I now can do is to delete the info, but I still have a blank area between the Header Bar and the my library list. It says "Empty (click here to configure)" just below the Panes and Options buttons.
Previously I had nothing but an horizontal splitter bar between the two lists. Now, between two splitter bars is a Header Bar and a Panes area. Before the upgrade, I did not have to waste screen area on this pane/scheme/header or whatever it's named.
BTW I never knew how to remove the Tree on the left side of the MC window, not that I wanted to do so anyway. Please explain this, especially if it is an identical process to removing the Panes, etc.