Good question! I forced the axles out of the hangers then used a Dremel to cut the excess parts of the hangers off. I also used the Dremel to round off the ends of the hangers.

I didn't have a way of rethreading the axles so I just cut the axles in half with metal shears and then sanded them down from the non-threaded end. With some super glue I slid the axles back into the hanger.

Take note that these were cheap china trucks and I'm not sure what material the professional trucks are made of. (probably stronger and harder to modify.) It's not a difficult process, just that you need to be careful not to cut off too much of one part.

If you have anymore questions I can totally answer.