Instructions
Using Kinect
Turn on the Xbox 360 and sign in to your Xbox Live account.
Hold your one arm against your right side and raise and bend your other arm at a 45-degree angle and wave your hand from side to side at the device until the Kinect Hub opens.
Hold your hand on the white message bubble icon at the bottom left. A red circle with a cross through the middle appears over the icon, indicating chat has been disabled.
Using a Controller
Turn on the Xbox 360 and sign in to your Xbox Live account.
Press the silver Xbox logo button in the center of your controller. The Guide menu opens.
Choose the "Chat & IM" option.
Highlight "Kinect Microphone" and press "A." "Off" appears below "Kinect Microphone," indicating you have disabled voice chat.