The webcam light on your Sony Vaio laptop computer will be illuminated for as long as your Vaio's built-in webcam is enabled. The entire purpose of this light is to let you know that your webcam is on and ready to be used at a moments notice. If you want to disable the light you'll have to disable the actual webcam. This can be done via a tool built into Windows that manages all of the hardware in your Sony Vaio.
Click "Control Panel."
Click "Device Manager."
Expand the "Imaging Devices" category in this window to reveal the icon for your Vaio's built-in webcam.
Right-click the webcam listing and click "Disable." The webcam light will go off because the webcam itself has been disabled. You will not be able to use the webcam again until you manually enable it.