If I'm reading this correctly, you've pulled the underdash and are now looking at a large black can that runs the width of the driver's side of the dash. That is actually the bolster. If I remember correctly there are three nuts/bolts that hold it in place, one at each end and the third hidden inside the can. Look in the access hole about the midpoint, you'll see it. Don't have to remove that one, just loosen it.
But as I recall, one doesn't have to remove the tube, only the underdash. Once the underdash is out of your way lay on the floor and you;ll see the cruise amp bolted to the brake pedal pedistal. !0mm box wrench is all you need to remove the single nut. Upon reassembly you'll need both hands, one to hold the bolt in it's recess and the other to start the nut.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.