code: public static void deleteUser(String username) throws RequestExecutionException
      {
          QueryProcessor.process(String.format("DELETE FROM %s.%s WHERE name = '%s'",
                                               AUTH_KS,
                                               USERS_CF,
                                               escape(username)),
                                 consistencyForUser(username));
      }
docs: Deletes the user from AUTH_KS.USERS_CF.
  
  @param username Username to delete.
  @throws RequestExecutionException