Adding or dropping a class can be done at UAOnline prior to the start of class and sometimes a day or two later. See the Dates and Deadlines chart.
Sometimes the option for making schedule changes is not available for short courses at UAOnline. In that case, you may complete the paper Add/Drop form or use the SSLL online Add/Drop form.
If you are withdrawing from all summer classes, complete the Total Withdrawal Form, not the Add/Drop form.
Check the Registrar's information on Withdrawing From Courses keeping in mind the various deadlines for withdrawing in the summer.