Use the admin panel password (the same one as the Teacher Panel's admin login, not the hub password).
This erases every student and teacher login and password, and their records: answer history, ratings, merits, games, classes, assignments and test results. Bash's account, his own keys and the site's content (questions, suspensions, reports without names, settings) stay. Deploy the change that removes the built-in accounts first, then make a dry run here.
For about a minute after the erase the site can still read the old accounts from its cache, and a sign-up, an approval or a grant save made then can write them back. So when the erase is done, or stops after it has emptied the accounts, keep this tab open: it waits 90 seconds, then makes the final dry run by itself, and if anything is left it says so and offers to erase it. Approve sign-ups and save teacher grants only after that. Run a dry run again tomorrow to catch anything an open tab or a scheduled job wrote back. Netlify's own function logs are outside the stores and cannot be erased from here.