My counsin, has this issue, I carefully took a dremel and a cut of disk. I ended up going thru 4 disks, they break easy.
good light is key, do mild cuts, and check, you an cut this in 2 or 3 places and it it will then spin righ off with your fingers. I was able to be carefull with the light cuts and not tuch or damage the threads.
A tip,
measure the distance of the nut to the threas of the bolt. you can then mark with a marker on the disk a line, this can help you also try not to cut into the bolt and threads.
Yes, the disk will grind down and you may have to remark and adjust for this as the disk gets smaller. but better to take your time and try and put in a few safe guards then damage the bolt / stud.
Sporty