How to programmatically C# change/reset FTP password

How to Programmatically C# Change/Reset  FTP Password 

FtpWebRequest request = (FtpWebRequest)WebRequest.Create("ftp://" + hostid);
               request.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
               request.Credentials = new NetworkCredential(rackid, password);
               request.GetResponse();
               request.KeepAlive = true;
               request.UseBinary = true;
               request.UsePassive = true;
               request.GetResponse();