You don't need a 300 dollar desoldering gun. If you already got flux and a regular soldering iron/gun all you, all you need is a 10 dollar solder sucker.

Here is what I use, https://www.amazon.com/WEmake-WM-SP4-Solder-Sucker-desoldering/dp/B0002KRAAG

Push down the black plunger on top till it locks in place, melt the solder on the board with your regular flux and iron, quickly place tip of sucker on molten contact. Then press the little black button on the side of the sucker, it releases the plunger sucking up the solder.

3-4 is a solder sucker - https://www.amazon.com/WEmake-WM-SP4-Solder-Sucker-desoldering/dp/B0002KRAAG