Alarm Sounder / Klaxon Tamperproof Nut Removal - Solved

[MikeP]

Hi,
Does anyone have ideas for removing the tamperproof nut on the alarm sounder?
Mine is mounted on a bracket under the fusebox and the bracket is folded in a U preventing access from the side

 

[Rudyrov]

You'll need to cut the nut off if you want to reuse the stud or bolt. It all depends on your intensions for it's removal.

 

[MikeP]

So, after much cursing I finally found a way to undo this nut without causing any damage (except to the nut) .......
BMW helpfully left a small rectangular cut-out in the side of the mounting bracket and by inserting a sharp, flat head screwdriver through this slot I was able to dig the corner of the blade into the nut then, using the cut-out as a fulcrum, lever it round.
Hopefully this might help someone else save a few grazed knuckles