This feature is the first option you find in the VR Toolbar settings. It is located in the rightmost item.
Just open the VR toolbar using TAB. Then, in the rightmost one, the cog, you’ll find the “Reset Panels”.
Again, based on my experience, it is better to make sure the popups are closed before doing it. I also use the settings to disable panels I don’t use since it has been reported to offer some FPS gains (which I never really measured).