Unfortunately, with the moulded box, you cannot just remove it from the backside.
The hinge screws are apparently only accessible from the top.
Have you looked at possibly drifting the hinge pins out?
From the centre, I think you can just hit the end of the hinge.
Worst case, a cutoff wheel and cut the hinges.
I think the edges are exposed when the door is shut.
That said, the catch bracket that screws to the box itself, can you get a small flatbar in the upper gap and force the catch upwrd a bit to release from the latch?
There is a back plate in the box, but it also screws in from inside the box, and I don't think there's enough room behind it to get into the box even if you could get it off.