public function deleteCharts()
    {
        //check whether workshett name is set or not
        if ($this->worksheetName == '')
            throw new Exception('Worksheet name not specified');
        $strURI = Product::$baseProductUri . '/cells/' . $this->getFileName() . '/worksheets/' . $this->worksheetName . '/charts/';
        $signedURI = Utils::sign($strURI);
        $responseStream = Utils::processCommand($signedURI, 'DELETE', '', '');
        $v_output = Utils::validateOutput($responseStream);
        if ($v_output === '') {
            //Save doc on server
            $folder = new Folder();
            $outputStream = $folder->GetFile($this->getFileName());
            $outputPath = AsposeApp::$outPutLocation . $this->getFileName();
            Utils::saveFile($outputStream, $outputPath);
            return $outputPath;
        } else
            return $v_output;
    }