You could do this. Doing so would make it a regular - non usb mic. You would then need to keep the original internal components and solder a female 1/4 plug onto that so you can plug the mic back into the USB portion when needed as a USB mic.

Or you could just save the money you would spend on time and random usb and 1/4" plugs cords and buy a microphone (although it would be a fun experiment to turn the usb portion of the mic into a "universal" USB audio input).