It depends on how it was inserted. It might have a nut that is attached to it that's counter-acting at the end or it may be smashed in place.
While not a carry handle, I did once had the acog mount get stuck into place and couldn't remove it. What I did was used a hacksaw to cut the knob down. It took me about an hour or so and a lot of aluminum debris came off but I finally got it off. Luckily I was replacing the mount so it didn't matter that it broke.