Resetting the Class Code
If you wish to change the Class Code, you can reset it.
To do so, log in to the Admin Console, access the "Classes" menu from the management screen, open the respective class page, and click on "Reset" next to the "Class Code" to reset it. Note: Resetting the code will not automatically remove students who have already joined using the previous code.
https://gyazo.com/ae2759dd0241ace82f3d5e87f80572ee
Reference