While you can drill, chisel and punch the "head" of the shear bolts out, I use a different method.
Take a die grinder with a 1/16" thick cut-off wheel and slice into the diecasting and the heads of the bolts. This makes a screwdriver slot. You might find a screwdriver can then be used to remove the bolts. More likely, you'll need an impact driver to back them out. Regardless, cutting and using the slot is fast and easy compared to other methods.
When you put the lock back on, don't buy new shear bolts (unless you really think a thief is going to look to see what fasteners are there). Instead, visit the hardware store and buy regular socket head cap screws. Check to confirm this... but I believe the locks use common 5/16-18 (coarse) threaded bolts.