Locate the four solder joints (connected to the yellow, black, blue, and red wires) on the bottom part of the phone, connected to the speaker. It will appear as a black circular part with some holes in it.

Place a piece of solder wick on top of the solders.

Very carefully, place the tip of the soldering iron on top of the solder wick. Hold it steady until the solder is soaked up into the solder wick.

Cut off the used solder wick with pliers and repeat this step if any solder remains.