Families and students cannot join classes using the class QR code after the class has been archived. The class needs to be active and in your class list to connect parents or students.
However, item QR codes will still work for items in archived classes. If you delete the item or the class, the QR code will no longer work.
To archive a class, tap your profile icon and then select the class you'd like to archive. Then tap the Wrench Icon (top right), scroll down, and tap Archive Class.
To restore an archived class, tap your Profile Icon > Gear Icon > Account Settings > Scroll down to Manage Archived Classes > Select the class and hit Restore. The class will be re-activated.