You can get special nozzles for hot air guns, but they are £££££££'s.
There's a lot of metal around that socket, which isn't going to help matters.
Is it possible to remove the top part of the socket? You them might be able to clamp the board vertically in a vice and remove the pins one by one with a pair of tweezers, while heating each joint on the back with a hot iron. You'd then need to go round and use a solder sucker or braid to clean each individual hole.
Whatever you decide, great care will be needed.