Remove sticky menu / header

Your site looks great!

Take a look for this code – position: fixed; in your style.css file around line 1156 –

/* # Site Header
---------------------------------------------------------------------------------------------------- */

.site-header {
	background-color: #fff;
	border-bottom: 1px solid #ddd;
	left: 0;
	position: fixed;
	top: 0;
	width: 100%;
	z-index: 999;
}

Depending on how you edit your CSS, you can either remove that line, change it to position: relative; or add your own Custom CSS code to override it.

If you plan to add your own Custom CSS code, you can try adding it to the Customize > Additional CSS page in the customizer like this –

.site-header {
    position: relative;
}

That may open up some space on the homepage under the header. If it does then you can adjust the margin-top (140px) around line 631 in your style.css –

.site-inner {
	background-color: #fff;
	clear: both;
	margin: 140px auto 40px;
	position: relative;
	z-index: 9;
	-word-wrap: break-word;
}

Let me know if that works.