As a CritterCoin admin, you can delete every Favorite Group created by all of your teachers. This is typically only done at the end of the school year to clear them out in preparation for the new data.
1) Sign in to the CritterCoin admin portal.
2) Click the Settings left side menu
3) Click the Delete all teachers' favorite groups button and confirm.
NOTE: After pressing the button, the deletion process can take several minutes, while the servers move through all of your teachers and delete their Favorite Groups. If you are planning on adding new groups, after this, to be safe you should wait several hours to ensure the deletion process is finished and your new groups do not get deleted.