Can the "Bolt of Mass Destruction" destroy walls?
I assume you mean a Bolt of Mass Destruction?
In which case, in my experience yes, they do destroy walls - first time I ever found the bolt I got a pair and tried one out a short time later to see what they did, I completely took out one end of the "archery practice" shaped room I was in (although, not the targets on the walls, so they clearly don't destroy everything).