If you would like to archive a particular class, select the gear in the upper right corner and then scroll down in the screen to where it says Remove from class list. It will then ask you if you would like to perform this action.
If you would like to bring a class back from being archived, select your name (upper left) then account, and then archived classes. you can then restore the archived class you wish to bring back.
Embedded below is a GIF followed by a 37 second YouTube tutorial.
As always, any questions please let me know.