A quick release steering wheel is a performance steering wheel that securely attaches to the steering column by means of cams, push or pull rings or pins. Most steering wheels are attached to the steering column by means of a large nut that is usually hidden by some trim pieces. A quick release wheel does away with the trim pieces for the performance and racing environment. This type of wheel is usually coupled with a collapsible steering column to enhance safety, and allow the driver of a high performance car enter and exit the car quickly and easily in the event of an emergency.
For more info, see How to Choose a Sports Steering Wheel