On phone, might be inaccurate 
but you can do a couple of ways:
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Steam VR / Settings / Chaperone / setting = ‘Developer’, but that leaves the floor box (not that noticeable). On the Rift touch controllers, press the left ‘properties’ button (under the X) to get to settings dash.
-
Do a Steam VR set-up, but choose the ‘Standing/Seated’ option, and it’ll remove chaperone graphics after about 10 seconds of sitting down.
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Steam install directory, config/steamvr.vrsettings - set CollisionBoundsColorGammaA to 0 (it makes it all go invisible) but google check this one, as not 100% sure.
EDIT: For the last one, in the steamvr.settings put the following in as a line to completely remove chaperone (although don’t bump your head and blame me 
):
