how do i convert rtf text to plain text

class ConvertToPlainFromRTF

{

    static void Main()

    {

        // If your RTF file isn't in the same folder as the .exe file for the project,  

        // specify the path to the file in the following assignment statement.  

        string path = @"test1.rtf";

        //Create the RichTextBox. (Requires a reference to System.Windows.Forms.)

        System.Windows.Forms.RichTextBox rtBox = new System.Windows.Forms.RichTextBox();

        // Get the contents of the RTF file. When the contents of the file are   

        // stored in the string (rtfText), the contents are encoded as UTF-16.  

        string rtfText = System.IO.File.ReadAllText(path);

        // Display the RTF text. This should look like the contents of your file.

        System.Windows.Forms.MessageBox.Show(rtfText);

        // Use the RichTextBox to convert the RTF code to plain text.

        rtBox.Rtf = rtfText;

        string plainText = rtBox.Text;

        // Display the plain text in a MessageBox because the console can't   

        // display the Greek letters. You should see the following result:  

        //   The Greek word for "psyche" is spelled ????. The Greek letters are

        //   encoded in Unicode. 

        //   These characters are from the extended ASCII character set (Windows 

        //   code page 1252): âä?å

        System.Windows.Forms.MessageBox.Show(plainText);

        // Output the plain text to a file, encoded as UTF-8.

        System.IO.File.WriteAllText(@"outputplain.txt", plainText);

    }

}