fast-xml-paser remove unwanted tags

Question

So every time that i want to build a new xml file the xml builder adds xml and stylsheet tags i would much rather add them myself or know how i could edit the content inside of it since i need to link the document to a specific stylesheet.

<?xml></?xml>
<?xml-stylesheet></?xml-stylesheet>
<schedule>
  <event>
    <title>IMY 210 Classes</title>
    <type>Event</type>
    <date>
      <day>2</day>
      <month>March</month>
      <startingTime>03:30 PM</startingTime>
      <endingTime>04:30 PM</endingTime>
    </date>
    <guests>
      <guest>
        <name>Yan</name>
        <email>[email protected]</email>
      </guest>
      <guest>
        <name>Daddy</name>
        <email>[email protected]</email>
      </guest>
    </guests>
    <venue>IT building</venue>
    <description>World worst brain surgeon giving class on XML.</description>
  </event>

this is the output but i want lines 1 and to go the passer that i use is called fast-xml-paser

and here is my code for writing this into a file the code get a JS object and appends it to the current JS ob that has the previous code on there from that i just go and re wright into the datafile but then i get the above mentioned output

app.post('/data', (req, res) => {
    res.header("Access-Control-Allow-Origin", "*");
    const parser = new XMLParser();
    const options = {
        processEntities:false,
        format: true,
    }
    const builder = new XMLBuilder(options);
    var oldJ;
    fs.readFile(dataFile, (err, rdata) => {
        oldJ = parser.parse(rdata);

        var num = Object.keys(oldJ).length;
        console.log(num);
        // res.send();
        // oldJ.schedule['event'][num] = req.body;

        var ans = builder.build(oldJ);
        var xmlheaders = '<?xml version="1.0"?><?xml-stylesheet type="text/xsl" href="output.xsl"?>';
        // oldJ.schedule['event'][]
        fs.appendFileSync(dataFile,ans, (err) => {
            if(err)
            throw err;
        })
        res.send(ans);
    });