you need to drill out the spot welds around the windshield flange, which are usually right on the edge of the flange, and carefully do the same on the brace [that goes where the steering column hangs on the dash to the inside of the firewall] .... this is not a fun job, and you'll likely break more than 1 drill bit .... you could also cut the windshield pinch flange right off and fab a replacement piece, but it's critical you get that windshield pinch weld back to the right size, shape and thickness to fit the windshield rubber ... sometimes [most times?] it's better to cut out bad sections and patch them rather than replacing the whole dash - either way requires some welding and bodyworking skill
Bill
