We've added the feature request to delete a school or cohort. Check out the new delete icon to the right of the school/cohort name on the School/Cohort District Management pages. Members and Managers of the school/cohort will not be deleted, but will be unassigned from the group. The ability to select the school/cohort in the Comparison Stats on the Dashboard, start a Discussion with the group, filter users by the group, etc. will be removed. This action cannot be undone, but should be helpful in cleaning things up if fake schools/cohorts have been added to any districts for demonstration purposes.