Here are some steps to help you with the desoldering process (at your own risk):

1. Heat the soldering iron up to your desired temperature (most commonly 300-400C is used).
2. Compress the spring of the desoldering pump by pushing its rod down. It should rest in its down position if done correctly.
3. Tin the soldering iron tip with a bit of fresh solder. 
4. Place your iron gently onto the joint you wish to remove, for no longer than 3 seconds. If you don't see the solder joint melt, do not leave the soldering iron on for longer, or you risk lifting a pad! Instead, consider introducing more fresh solder onto the joint or slightly increasing the temperature.
5. As soon as the solder joint is melted: remove the soldering iron, immediately cover the entire joint with the desoldering pump, and press the yellow button on the pump to release the spring. This step needs to be performed very quickly or the solder will solidify.
6. Ideally, all of the solder is removed from the pin. Visually inspect to make sure all solder is removed from the switch pins before attempting to remove switches. You may need to repeat Steps 2-5 to remove any remaining solder.