I had the same problem when I removed my forks to install the lowering kit. This works . Put the broom in the fork and then put a pipe clamp used for wood working on the end of the leg and the other end on the end of the handle. tighten it up and she will loosen up. The end of the damper rod will then be held from turning. Then you can use a reg. socket to loosen the bolt.
Willy