Bütün dosya ve klasörleri silmek.

string strTempFolder = "C:\\temp";
DirectoryInfo dir = new DirectoryInfo(strTempFolder);
                    
foreach (DirectoryInfo di in dir.GetDirectories())
{
  System.Array.ForEach(Directory.GetFiles(di.FullName),delegate(string path) 
  { File.Delete(path); });
  Directory.Delete(di.FullName, true);
}