These are pretty awkward to remove, but once you understand how they work its easy enough. The goal here is to slot the spudger THROUGH the gap of the silver tabs (visible in previous steps image, circled) and then pry. Put pressure against the wall of the Xbox case and push downwards, once you feel the spudger slot in, then apply force away from the Xbox and pull up a little with your free hand.
Thanks for the guide guys, much appreciated. When I order the new screen I’ll update this comment if there was anything interesting about my heatsink repasting.