Originally Posted by
Jeff Wills
Those are old Shimano single-pivot brakes. They were always evil to get and keep centered on the wheel.
It looks to me like the bolt has flats for a cone wrench, and that there's probably enough clearance for the cone wrench to get past the lower cup:
If you have clearance problems with the cup, remove the brake and add a washer to move the flats further out to where you can grab them with the cone wrench. Once you're at that point the rest is easy.