Saving XML file after delete particular node in Windows Phone 8.1 RT

I am developing an app that saves some values initially for settings and after usage, it automatically delete them and save the XML file again. I am using the below code, the app load the XML but its not deleting the node nor saving the file. Can anyone help me to this.

        XDocument definitionFile = XDocument.Load(@"definitions.xml");

        XDocument definitionFile = XDocument.Load(@"definitions.xml");

        var wordset = definitionFile.Descendants("wordset");
        int wordsetCount = wordset.Count();
        var randomWord = (from word in definitionFile.Descendants("wordset")
                          select word).OrderBy(r => rnd.Next(0, wordsetCount - 1)).First();

        selectedString = randomWord.Descendants("word").SingleOrDefault().Value.ToString();
        selectedMeanings = randomWord.Descendants("meaning").SingleOrDefault().Value.ToString();

        string scrambledString = ScrambleWord(selectedString);
        txtQ0.Text = scrambledString.ElementAt(0).ToString();
        txtQ1.Text = scrambledString.ElementAt(1).ToString();
        txtQ2.Text = scrambledString.ElementAt(2).ToString();
        txtQ3.Text = scrambledString.ElementAt(3).ToString();
        txtQ4.Text = scrambledString.ElementAt(4).ToString();
        txtQ5.Text = scrambledString.ElementAt(5).ToString();
        txtQ6.Text = scrambledString.ElementAt(6).ToString();
        checkSetHighScore();

        //removing the node part
        randomWord.Remove();
        Stream stream = new MemoryStream();  // Create a stream
        definitionFile.Save(stream);      // Save XDocument into the stream
        stream.Position = 0;

Remember this is Windows 8.1 RT (not Silverlight)