When exporting to html I get the following in the footer:
That's HTML postamble, see (info "(org) HTML preamble and postamble")
.
is it possible to remove the "Created" and "Validate"?
Yes, use #+OPTIONS: html-postamble:nil
or (setq org-html-postamble nil)
.
How to place Author and Date under title?
One solution is to use HTML preamble, for example,
(setq org-html-preamble-format
'(("en"
"<h1 class=\"title\">%t</h1>
<p class=\"subtitle\">%d BY %a</p>")))
and to avoid showing two titles, you also need to use #+OPTIONS: title:nil
to discard the default title.
Here is a simple org-mode file
#+TITLE: A simple org-mode file
#+DATE: <2018-10-07 Sun>
#+AUTHOR: someone
#+OPTIONS: title:nil html-postamble:nil html-style:nil html-scripts:nil html-doctype:html5
#+HTML_DOCTYPE: html5
blah blah blah
after setting org-html-preamble-format
as above, the HTML export will be
<!DOCTYPE html>
<html lang="en">
<head>
<!-- 2018-10-07 Sun 13:18 -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>A simple org-mode file</title>
<meta name="generator" content="Org mode">
<meta name="author" content="someone">
</head>
<body>
<div id="preamble" class="status">
<h1 class="title">A simple org-mode file</h1>
<p class="subtitle">2018-10-07 Sun 00:00 BY someone</p>
</div>
<div id="content">
<p>
blah blah blah
</p>
</div>
</body>
</html>