code: public void revokeAll(IResource droppedResource)
      {
  
          UntypedResultSet rows;
          try
          {
              // TODO: switch to secondary index on 'resource' once https://issues.apache.org/jira/browse/CASSANDRA-5125 is resolved.
              rows = process(String.format("SELECT username FROM %s.%s WHERE resource = '%s' ALLOW FILTERING",
                                           Auth.AUTH_KS,
                                           PERMISSIONS_CF,
                                           escape(droppedResource.getName())));
          }
          catch (RequestExecutionException e)
          {
              logger.warn("CassandraAuthorizer failed to revoke all permissions on {}: {}", droppedResource, e);
              return;
          }
  
          for (UntypedResultSet.Row row : rows)
          {
              try
              {
                  process(String.format("DELETE FROM %s.%s WHERE username = '%s' AND resource = '%s'",
                                        Auth.AUTH_KS,
                                        PERMISSIONS_CF,
                                        escape(row.getString(USERNAME)),
                                        escape(droppedResource.getName())));
              }
              catch (RequestExecutionException e)
              {
                  logger.warn("CassandraAuthorizer failed to revoke all permissions on {}: {}", droppedResource, e);
              }
          }
      }
docs: Called after a resource is removed (DROP KEYSPACE, DROP TABLE, etc.).