Go to UCONNECT. Use the Enroll, Add, or Drop link in the Registration Tools channel, and in the form that pops up you'll see the classes in which you are currently enrolled. Click on the dropdown arrow to the right of the course you wish to drop, and choose the drop action. Your choices will be "Web Drop, W grade, NO refund" or "Drop Course or Waitlist, Refund" depending upon when you're dropping.
Please note: Complete Withdrawals (dropping all classes) after classes have started must be done in person at the Office of Undergraduate Admissions in NUC 124. You will not be permitted to drop your last class via the web.