How to remove molding at rear edge of vinyl top

they are held in by clips which are attached with nuts from below

Yep. They are really obvious if you look up from inside the trunk. There are 7 of those going across the Dutchman panel and 6 of the plastic clips that mount onto the "nail heads" at the base of the C pillars. EDIT: The previous numbers are wrong. In case anyone is counting, on each side (C pillar) there are actually 3 plastic clips and one screw-in clip, and on the back there are 4 plastic clips and 5 screw-in clips. So the total is 10 plastic and 7 screw-in (1974 Dart).
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And here's a close-up of one of the plastic clips:
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