The bottom two are shear bolts.
You need to do one of two things:
1) reverse drill them with a special drill piece. This basically will grip the bolt and wind it out.
2) Either chain drill a slot into it or hit a blunt chisel into it to create a slot for a screw driver. Then unwind it, it will not be easy though.
Good luck
Lord Godley The Third, February 2011
