How to disable and re-enable a class
This will open the 'Edit class' menu. From here you can click the 'Disable class' button which will archive it.
The class will now display as a greyed out archived class, and can be re-enabled by a user with admin privileges.
To re-enable the class, they simply must reopen the 'Edit class' menu for the disabled class and click the 'Enable class' button.