Moriwaki headlight bracket.

[pekingduck]

First, it's not a terribly difficult job. The top clamp only needs to be moved up 1/2" for that bracket to clear. You will want the bike on the centerstand, the tank covered top and sides with a heavy blanket or a thick jacket (no zippers or buttons).

Remove the handlebars and lay them on the tank carefully - nothing needs to be disconnected, nothing will leak. Remove the top stem nut (30mm), and for added precaution, clamp the handlebars back in place securely so they don't move around on the tank. Now loosen the pinch bolt on either side of the top clamp a couple turns.

With a plastic or rubber hammer, tap gently on the underside of the top clamp, alternating side-to-side, so that the top clamp comes up about 1/2"-5/8" - definitely no more. You do not want to slide the tubes out of the top clamp, just for convenience.

The bracket should slip out. Reassemble by tapping the top clamp back down evenly, tighten and torque the center nut, then tighten and torque the pinch bolts.
Second, if you don't want to do that, and don't forsee re-using that bracket, there are a couple alternatives. In all cases, keep that tank covered up to protect it. An ounce of prevention.......

With the headlight case off, you can cut the bracket rods with a bolt cutter (if you or your friends don't have one, you've led an exemplary life). Harbor Freight has a 12" for less than $10, which should be adequate.

Third, you could use a grinder/cutting wheel, but that will get fine metal particles everywhere. And if you had to re-use it, you could weld it, file smooth and repaint it, or buy a new one. The bracket is about $100, about what a shop charges an hour.