@ProfessorPlum168 It is as simple as logging onto a site and drop the class.
@kjake2000 Anything you drop within 2nd week of instruction does not get a fee. (Expand the ‘Late/Enroll/Drop Fees’ tab in https://registrar.berkeley.edu/tuition-fees-residency/tuition-fees)
Except for a handful of classes that have early drop deadline which is the 2nd week of instruction anyway, you can take the class up to 4 weeks. In most cases, 2 weeks is enough time to decide whether you want to continue with the class or not.