Pair of long nose should hold that from spinning - you only need to drill enough of the stud away so you can tilt it and extract the rest of it from underneath.
Dremel or similar with small cut off wheel, cut a slot in from above, using the small circumference of the disc to get it deeper, widen the slot to suit and use a big flat screwdriver to hold the stud.
If your lucky, it will hold well enough to undo, if not, it will hold enough to junior hacksaw or similar the remains out held from spinning.