I'd start out using solder-wick to soak up the solder around the connections.

[![enter image description here][1]][1]


Even with that though you will probably find it still sticks.

As such you need to sort or pry them apart by using a scalpel blade as a wedge starting in a corner are then use your iron to reheat the pads will they separate and then push in the wedge a little further to keep them apart. 

It is an exercise in patience. DO not be tempted to rush it or you will tear the pads off.

ALTERNATIVE 1: Use a hot air source, to heat it all at once. That though can be tricky to do without displacing everything else on both the daughter and mother board.

ALTERNATIVE 2: Add some heavy wire round the device so it touches every pad and use a couple of soldering irons and fresh solder to heat and solder the entire wire so it is all hot, and molten, at once, then remove the board and wire quickly before the solder sets.


  [1]: https://i.sstatic.net/Luco2.jpg