Actually it was the fist time for me doing this with rather modest tools.
I clamped the board in a small vise and used a spring loaded solder sucker to remove the solder from all the pins on both sides.
Ended up using plyes to carefully pull the Arduino from the board. Then pulled the remaining pinns from the board one by one.
I think the the most challenging part is to solder the new Arduino back in place and avoid "bridges" between the solder joints. A magnifying desklamp is your biggest friend.
kj6etl