I removed mine using an old pair of side cutters. With the thin edge on these they can grab the fattest part of the head flush to the rail, and twist enough to get them a tiny bit out, enough to grab with pliers and twist the rest of the way.
I gave this a go this morning. Worked a treat! Killed a set of side cutters but I was due some new ones anyway.
Quite a few nails snapped when removing them. Should I drill them out or any other suggestions?