It's just a stud screwed into a threaded hole in the fork. If you can get two nuts or a pair of vise grips on what remains sticking out after you remove the cap and axle, then you should be able to break it loose and screw it out. It doesn't look flush but if it is, then drill out the center and use a screw extractor. Cut a generic stud, threaded rod, or bolt (of proper thread size and pitch) to enough length and use two nuts tightened together on one end to screw it in tight. Maybe a dab of loktite if you're concerned about the possibility of it unscrewing from the fork when loosening the nut, but in reality it wouldn't matter.
Another reality is that you could have simply continued on your prescribed path and fixed this when you got a chance. I would have counseled you to simply tighten the one bolt at the top all the way so the clamp is flush with the fork, then use the bottom two to take up the slack - chances are, it could run the rest of the life of the bike that way. I wouldn't let it stop me from keepin' on.
Let's ride!!! - No offense, but there've been a lot of people over time who were just as sure, yet got it wrong. - Una necedad, aunque la repitan millones de bocas, no deja de ser una necedad. - "you know that I could have me a million more friends and all I'd have to lose is my point of view" (Prine)