How do i turn off my computers mic?

http://www.crashwiki.com/pvz-garden-warfare-disable-chat-disable-mic-use-push-talk-use-voip/

1. Right click speaker icon in system tray.
2. Select Playback Devices.
3. Select a Playback Device other than what you use for sound output.
4. Right click it and select Set as Default Communications Device.
5. Hit OK.
6. Left click on the speaker icon in the system tray.
7. Click the icon below the slider on the device you chose to mute it.

Do the same for Recording devices.  That will effectively turn your mic off.  The above does it so you don't hear them.