First you will need to log into your camera through its IP address. If you don't know what the IP address is you find this using the SADP tool. Just open up SADP while the camera is connected to your network; it will detect it and show you the IP address. It should look something like '192.168.1.200'. If the numbers are different don't worry, just enter it into the address bar in Internet Explorer. You should be presented with a login page; the username is 'admin' and the password is whatever you set it to be.
Next step, go to Configuration -> System (Advanced Configuration if it's an option) -> Service tab -> uncheck "Enable IR Light" and click Save
Configuration -> System -> Maintenance -> System Service -> uncheck "Enable IR Light" and click Save