How do I disassemble this column drop?

[Fullfendered]

Managed to remove column drops, drilled out pins, removed key cylinder, now how do I complete disassembly (remove On/Off switch)?

By the way I tried the "weld-a-nut-to-it" method to remove bolt, kept breaking off the nut.

Then I tried: I drill a series of 1/16 holes across the face of the pinch bolt. A little sideways action with a drill will produce a slot. Broke two screw drivers.

Got out the torch, get it red and this time the bolt came out and no broken screw driver.

As always, thanks in advance for any advice.