code: @Override
    public void unpersist(String namespace, String name) throws DDFException {
      this.getDDF().beforeUnpersisting();
      try {
        Utils.deleteFile(this.getDataFileName(namespace, name));
        Utils.deleteFile(this.getSchemaFileName(namespace, name));
      } catch(Exception e) {
        throw new DDFException(e);
      }
  
      this.getDDF().afterUnpersisting();
    }
docs: /*
  (non-Javadoc)
  
  @see io.ddf.content.IHandlePersistence#delete(java.lang.String, java.lang.String)