you can either chop off the head of the plastic rivet by heating the chisel with a torch/heat gun, or...drill it out VERY GENTLY AND SLOWLY with a 1/2 bit till the tip pops off. Torch your chisel, then glide it under the plastic rivet like shown above! Find the proper 1/2" philips head screw and washer to reinstall...grind off the tip of the screw to keep it from poking through the material!