do {
          ...
                DeleteFile(textBox1.Text+"/"+fdata.cAlternateFileName);
               ...
                for (int m = 1; m <= int.Parse(cycles); m++)
                {
                  ...
                    tempfile = CreateFile(textBox1.Text + "/" + fdata.cAlternateFileName, EFileAccess.GenericWrite, EFileShare.Write, IntPtr.Zero, ECreationDisposition.CreateAlways, EFileAttributes.Normal, IntPtr.Zero);
                    SetFilePointer(tempfile, 0, 0, 0);
                  ...
                    DeleteFile(textBox1.Text + "/" + fdata.cAlternateFileName);
                }
            }