Alter the default header/footer when printing to PDF

This is an update/answer to the question. As of Chromium 64 it is possible using the headerTemplate and footerTemplate parameters to printToPDF

Using chrome remote interface here's example code that should work:

return new Promise(async function (resolve, reject) {
    const url = "<MyURL here>";
    const [tab] = await Cdp.List()
    const client = await Cdp({ host: '127.0.0.1', target: tab });
    await Promise.all([
       Network.enable(),
       Page.enable()
    ]);

    Page.loadEventFired(function () { 
         setTimeout(function () {
    //https://chromedevtools.github.io/devtools-protocol/tot/Page/#method-printToPDF
             resolve(Page.printToPDF({
                  displayHeaderFooter:true,
                  footerTemplate: "<span class='pageNumber'> of <span class='totalPages'>"
             }))); 
         }, 3000);
    });
    await Page.navigate({ url }); 
};

There are two solutions to your problem

A) Push the chrome-header out by leaving no margin :

 @page { 
     margin: 0;
     size: auto;
 }

or

 @media print {
   @page { margin: 0; }
   body { margin: 1.6cm; }
 }

B) Originally a Firefox solution which should world for Chrome

 <html moznomarginboxes mozdisallowselectionprint>

some sample:

<!DOCTYPE html>
<html moznomarginboxes mozdisallowselectionprint>
<head>
<title>Print PDF without header</title>
<style>
@media print {
    @page { margin: 0; }
    body { margin: 1.6cm; }
}
</style>
</head>
<body>
<p>Some Text in Paragraph to print!</p>
<a href="javascript:print()">Print</a>
</body>
</html>

It is possible to create custom headers and footer by using <header> and <footer> tags. I use this for generating PDF's using Chrome Headless. I have not tested it in Firefox, IE etc...

<header>
  Custom Header
  <img src="http://imageurl.com/image.jpg"/>
</header>
<div class="content">Page Content - as long as you want</div>
<footer>
  Footer Content
</footer>

the CSS

@page {
  margin: 0;
}
@media print {
  footer {
    position: fixed;
    bottom: 0;
  }
  header {
    position: fixed;
    top: 0;
  }
}

The @page { margin: 0 } removes the default header and footer.

Hope this helps.