Question about Philips Hue Wall-mounted switch module for Hue lamps (battery-operated), single pack

Yes, you need to remove the initial switch, disconnect it from the power supply, attach the Philips system instead, connect it to the switch and put it back on as before. (The HUE system is then located between the electrical connection and your switch.

If needed, Philips has videos on their website explaining how to do this. :)