If you are changing your schedule, when you click Add or Drop Classes, you will see courses for which you are already registered, with a box labeled “Action” that has “None”. Click there, you have a choice of “Web Drop/Delete”. Change box to “Web Drop/Delete” for courses you no longer want. Scroll down to the blank boxes to enter CRNs for additional courses you want. When finished, click Submit Changes or these courses will not be dropped or added.