There are two answers. Both will work; the first is best.

1. Get a real kilt maker to tear the waist loose and redo the whole thing. It's quite a job of actually rebuilding the kilt, but it actually moves the waist line down, making the result a shorter kilt.

2. Ever so carefully cutting the selvege end. This is a tedious process and not for the faint of heart or shaky of hand. There are some very good instructions online about running a zig-zag stich and using some fray stopping stuff. It is my understanding that the regiments used this method.

I know, I know. You can hem it, but a kilt is not hemmed, and there is no way on earth that I will ever believe that a hem doesn't adversly affect the hang of the kilt. So let the slings and arrows of outrageous hemmers commence. I still would never hem my kilt, only my wife's skirt.