code: public void deleteColumnFamily(DBConn dbConn, String cfName) {
          m_logger.info("Deleting ColumnFamily: {}", cfName);
          try {
              dbConn.getClientSession().system_drop_column_family(cfName);
              waitForSchemaPropagation(dbConn);
          } catch (Exception ex) {
              throw new RuntimeException("drop_column_family failed", ex);
          }
      }
docs: Delete the column family with the given name. The given DB connection must be
  connected to the keyspace in which the CF is to be deleted.
  
  @param dbConn    Database connection to use.
  @param cfName    Name of CF to delete.