To rename a class, head over to the class overview page of one of your classes. Here you can select the "Settings" tab, where you can edit your class settings. You can edit the name, archive or delete the class and remove or add courses to the class. Make sure to press Save once you've finished editing.

If your school has the School Sync package, you won't be able to rename your class. If you need to, ask your Data Manager or IT Department to update the name for you in the school's MIS.