[zabzonk]

Or simply by unplugging the mike?

[brewdad]

At which point the system will helpfully switch to the built-in mic.

[zabzonk]

As it might/probably will happen by turning off the USB port.

[leethargo]

I can disable the on-board sound card in the BIOS settings on my Thinkpad (T440p), so unplugging the USB headset should do the trick (but then there's no music either).