1977 Monte Carlo Bumper

ok i need to take off the chrome faceplate of the rear bumper on my 77 monte theres bolts on the bottom of it and t bolts along the ontside and a couple carriage bolts

ive removed the bolts on the bottom and lossened the t bolts but they dont come out and the faceplate doesnt budge. am i goin to have to grind the heads off the carriage bolts?

thanks any help would be great i dunno wat else to do