They are not easy, as you seem to have found out. Lots of heat applied to both sides - 300-330C is probably in the right region. You probably aren't going to reuse that socket so you can be a bit rough with it, just be mindful of the traces underneath it. Heating from above and prying at it bit by bit it should start to pull apart pretty easy. Very destructive but I've found this the easiest way to remove them.Anybody have any tips on de-soldering SIMM connectors?