Someone correct me if I'm wrong, but I'm not sure that's possible? With ALL those legs, I'd think the only way to remove it is to cut it off, then remove the remaining leg pieces individually, then solder on a new chip (if re-using this same board, which you're not). Otherwise, I don't know how you could heat up and keep enough heat on enough legs at the same time to remove it without it becoming solid solder points again, there's just too many. Can't you just buy a new chip, or does that chip contain data or something irreplaceable? Maybe someone else can chime in who has much more experience than me if there's a way to do it, but I've seen chips with a LOT less legs than that where the feasible way to do it was cut the legs.