Dropping a class is very similar to the way you signed up for it.  Log into your student portal on WebReg, click on the Add/Drop/Register tab on the left side of your screen, and select the term.  A list of the classes you are currently registered in will display on the page.  To the far right of each class is a highlighted blue DROP link.  Click on the DROP link and follow all of the instructions and prompts to complete the drop process.  You can confirm the transaction was recorded by returning to the Add/Drop/Register tab and viewing your list of classes again to make sure the dropped class has been removed from the list.