tonkski used his keyboard to write :
I have a roof ladder which has bearer brackets every few rungs, which stand
it off the roof a few inches. I need to move one of these brackets. I'd like
to make sure I remove the bracket without destroying it or the ladder. The
bracket is secured to the ladder with what I assume is some kind of rivet
(there's nothing sticking out of the opposite side of the ladder). Here's a
photo: imgur.com/a/FuAVreC

What kind of rivet is this, and how do I best remove it please? I have a
drill and an angle grinder. Ta.

Its an heavy duty pop rivet. Either use a drill bit, but have pliers to
hand to grip the rivet when it begins to spin under the drill, or you
could grind the head off with the angle grinder.