How to close an area? With a UI layout like this:



How do I close the bottom area?

These are the context menus of the header, the split, the editor type selector and the type selector itself:

   

There's an item that allows me to maximize the area, but there is nothing to close it.
Ok, I found one weird way:

I can split the bottom area vertically as well and then align the split borders of the top and bottom area pairs:



This alignment is easily possible because the split borders snap to a grid.

As soon as they are aligned, the context menu of the border between any top and bottom area gets a new item "Join areas":



After joining the left pair and the right pair, the bottom area is then gone.