I want to replace my bike's stem cap, but it seems to have a cover over the bolt that I can't figure out how to remove. I've tried loosening the bolts that are underneath it, but that didn't seem to make a difference. It's in there fairly tightly, I don't think I can lever it out without doing damage.
There is absolutely a large bolt that runs down the center of your steerer tube and interfaces with a star nut or similar. This is required to set the preload on your headset bearings.
I am unfamiliar with this exact top-cap but there must be a way to access that bolt. If you examine your replacement stem cap, it should be a metal disk with a hole in the middle for the bolt.
I suspect the black disk with the FDKOBE wording is a clip-on cap, either clipped around the edge or perhaps in the middle. That bulge in the middle will be where the bolt's head is, probably a 6mm hex though other sizes may be used.
Try and lever it off around the outside seam.