What is a cleansing brew and how do I run one?

A cleansing brew is an initial rinse cycle that prepares the coffee maker. For single cup: press the POD button, do not insert a K-Cup pod, press the 8 button, then press the brew button. For carafe: press the CARAFE button, press the 8 button, then press the brew button. Do not fill the filter basket with coffee grounds. The initial heating process takes about 4 minutes, and pour the hot water into the sink when complete. (Page 2)