c# popup close selenium

String parent = driver.getWindowHandle();

        Set<String> pops=driver.getWindowHandles();
        {
        Iterator<String> it =pops.iterator();
        while (it.hasNext()) {

            String popupHandle=it.next().toString();
            if(!popupHandle.contains(parent))
            {
            driver.switchTo().window(popupHandle);
            System.out.println("Popu Up Title: "+ driver.switchTo().window(popupHandle).getTitle());
            driver.close();