Clarifying shampoo!!!!!!!?

Ok so I dyed my hair and got some answers on how to lighten it up. I was told to use clarfying shampoo and then rinse with HOT water! First, is this the right thing to do? Second, how much of the color will it take out? And third, what is a clarifying shampoo? haha I have no idea what it is. Can I buy it at a drug store and what are some companys that make it? (Pantene, Tresemme, Suave, etc.) HELP ME PLEASE!!!!