Any way to remove the "places" bar permanently?

The "Places" bar is a great idea but currently useless, as it opens tabs and thus wastes double the space.

So I remove it through the GUI, but it seems with every update or even restart (??) it resets itself to visible again, which is a major annoyance.

I searched in the about:config and couldnt find the config? I would place it in my already existing hardened user.js