Latitude E6430 mic goes to audio out

I was playing around with my sound card options and must have messed something up.  My external microphone now goes directly to my audio output - either to my external speakers or (if i have headphones plugged in) to my headphones.  I can't disconnect it.  If i run something like iTunes, it will play the iTunes audio, but i'm still getting the external microphone sound on top of the iTunes audio.  How do i disconnect the microphone from the audio output?

i'm running Windows 7 Professional SP1.

Thanks