take everything off the other side and tap the axle through a bit , loosen the arm and push against the BB/spacers ( hoping you have enough spline to do so ) this should leave the bolt head proud of the arm and you could either file 2 flats on it and use a spanner/adjustable or some decent mole grips
ill assume you have loosened the pinch bolt already and given it a good soaking of wd40/gt85
its worth removing the pedal , you will no doubt hit your hand on it once the bolt decides to let go and pull towards you instead of push away , saves punching the floor