I am bringing up an old post, because I finally got to mine to see how to take it out. It did not come out easily. After hitting the shaft with a nut attached, we had to heat the inner shaft and pull at the same time. It wasn't easy with the heat either!
The handle locked you should not prohibit you from removing it. There is a pin that comes out in the locked position that stops the handle from turning, but you should be able to manipulate it through slot in the hole. You may have to remove the four bolts first to let it slip through the hole. If that doesn't work, I think that the latch should come out without the handle, either way, you should be able to remove the handle in the locked position.
(After thinking this through, it would be a hassle to remove a locked stuck handle. The pin would be at a vertical angle and the slotted hole is at a horizontal angle. Trying to pound the shaft out without damaging the sheet metal lid would be next to impossible. You will have about a 1/4 inch to pound before it hits the sheet metal, twisting the latch may help, but I am not sure how much it will turn in order to be lined up with the slot.)
Be careful when tapping on the threads, even with a nut on them, I managed to do slight damage. I was able to repair mine, but I would hate to see you go through all of the work taking it out just to have more work to do.
Now to a locksmith to get a key made.
