title: How to clear text content in RichTextBox
body: <p>After getting the text in the RichTextBox I want to clear the text. How can I do that?</p>
  
  <pre><code>TextRange txt = new TextRange(richtxtSNotice.Document.ContentStart, richtxtSNotice.Document.ContentEnd);
  MessageBox.Show(txt.Text);
  </code></pre>