I am using duolingo as a teacher. Three of my students put in a password they have no idea what it is. Our school email address does not allow them to receive emails from out of the district. Any chance their accounts can be deleted and they can start over? They aren't in my class yet, so I can't see or make any changes on my own.
No, if they aren't in your class yet, they'll just have to start over. Chances are though, they haven't done more than one skill if they forgot already, right?
Once they are in your class, you can re-set their password. So make sure you are standing over their shoulders when they make new accounts, and have them enter your class immediately.