Are you talking about the interior plastic one? If so, you have to undo half the screws on the top windshield molding and loosen it. You also have to yank down (hard) on the molding strip over the door so the plastic molding is free on top. Getting the molding off, after you've undone the screws, involves a gentle twisting motion with the part by the corner of the windshield coming off first. Sometimes when new windshields have been installed, the mastic gets under the molding and glues it on, so then some careful action with a razor blade in called for.
