Surprised nobody replied to this one already.
Anyway, if you are still looking to do this, here is how:
1. Go to "
Control Panel"
2. Open "
System"
3. Click the "
Hardware" tab
4. Click "
Device Manager"
5. Expand "
Sound, video and game controllers"
6. Right-click on the name of your old sound device.
7. Click "
Disable" on the menu that is displayed after step 6.
8.
Save and close.
That should work for you.
However, you don't really even need to do that. I suggest the following steps to simply change your default sound device. This way you can still use your other sound card for TeamSpeak or other forms of voice chat without having to hear your music and sound effects out of your headset.
1. Go to "
Control Panel"
2. Open "
Sounds and Audio Devices"
3. Click the "
Audio" tab.
4. Specify your "
Default device" in the drop-down menus
5.
Save and close.
Hope that helps!