How to remove solder?

Solder has to be heated in order to melt it for removal, usually by a soldering iron. Then the removal methods can vary. You can get a braided solder remover from a local electronics store that when applied to the melted solder will "wick up" the melted solder.

Then there's the vacuum bulb or vacuum hand held solder pump that is used by placing it on the melted solder and either by releasing the bulb or tripping a lever, will literally suck the solder from the connection.

Soldering is easy to learn but there are pitfalls if you're not familiar with the techniques, proper sizes of soldering irons, etc.