This happened to my allmost new Royce bb after i fitted it to my New Pace frame, without having the threads cleaned first.
You might be able to do the same…That is hammer the axel out, it is a bonus if the bearing goes with it and cut the cup out. You can tell when the hacksaw blade is just touching the top of the threads in the frame. Make 2 cuts (as if to take 1/4 out) then you should be able to hammer ( with a large flat screwdriver)the 1/4 piece inwards and loosen it. The rest should come away easy.
It will take maybe an hour but it is very satisfing when done. This one was by my mistake but i have done it before with really old ones as well.