How to close the "VST Instrument/mediabay" on the right

Hi to all…How do you close the “vst instrument/mediabay” window on the right side of the main window. I would rather have my main window have all the width to see more of my song on the piano roll instead of that window I don’t use.
I searched the internet and this forum and found that alt-T closed it in Cubase 8… but in cubase 9, it has no effect.
Any ideas?

If you look to the top right of your screen you’ll see three buttons, they control the visibility of the three panels, left, right and bottom (see also attached screen grab).
close panel.PNG