Late to the party, but…
Solder wick. It’s basically just flat braided copper wire. Search Amazon for “solder wick”. It comes in a huge array of sizes, brands, etc.
You use it to UN-solder things. Basically you lay it on top of the solder joint to be removed, put your hot soldering iron on top of that, then when the heat soaks through, the solder will liquify and be pulled into the wick. Remove wick while still liquid, let harden and then cut the end off (with the solder on it).
Think of it the way you’d think of an eraser for pencil marks.
Good for fixing mistakes, and for occasionally salvaging components from random electronics.