Place the tip of the solder sucker above the heated solder joint. Then push the sucker button to suck away the liquid solder.
Desolder using a solder wick
You can choose to use the wick from the roll or cut off a section and use it by itself. Cutting off a section is useful to avoid that heat gets transferred away from where you want it.
If you cut off a section, it can be smart to hold the section with tweezers. It can get really hot 😉
Start by putting the solder wick on the solder joint you want to desolder.
Put your soldering iron on top of the wick. After a few seconds you should see the solder getting wicked into the solder wick.
If the current section of the wick gets full of solder, cut it off and repeat the process until all the solder is gone.
Desoldering without any desoldering tools
If you don’t have a wick or a pump, you can still get by. This is not recommended, but might work if you’re desperate.
To remove an excess solder bridge
between two pads you heat the solder joint then poke around with the tip of the iron until the bridge is gone.
To remove a component from a PCB you fasten your tweezers on the component lead you want to remove, heat the solder joint and then pull and jerk the lead out of the hole when the solder melt.
My favorite technique used to be the soldering pump. But I have found that when you are dealing with smaller pads and pins, a solder wick is sometimes much easier to use.