Removing PCB from complex pattern of soldered-in thru-hole posts?
I'm assuming no access to the other side.  (Otherwise cut the pins and remove them one at a time.)  I like a solder sucker for this.  (But this also assumes none of the pads are connected to a  ground plane... It's sometimes hard to get enough heat into the ground pad pins.)  Make sure the solder sucker is clean (My has an o-ring that I will take out and re-grease.)  Then work hole by hole, sucking out the solder.  Then for that last bit of solder that holds the pin to the pad, heat it and try wiggling it with some tweezers until it is free... sometimes you can push it down a bit.  If this doesn't work then my only other thought is to try and drill the pins out.