To archive a class, go to your Manage Classes page. Click on the Options dropdown for the class you wish to archive and select Archive Class. Your class and all of its assignments will then be removed from "Active Classes" and saved on the My Archived Classes page.
If you would like to view any of your archived classes, later on, you can do so by clicking on the "Archived Classes" button on the Manage Classes page. You can also restore or undo an archived class by clicking on the "Undo Archive" button on the My Archived Classes page.
If your classes are synced from Clever, you cannot archive or delete these classes since they are managed by your school or district. However, you can hide Clever classes if you are not using them. You can hide Clever classes by going to Manage Classes and clicking Options > Hide Class. Once hidden, these classes will be saved under Hidden Clever Classes. You can always unhide classes by going to Manage Classes and clicking Hidden Clever Classes > Options > Undo Hide.