Delete sidebar in sider template

Hi there,

You can remove that functionality by removing the first 66 lines of code in Customize > Additional CSS.

More specifically, you don't need this:

@media (min-width: 1000px) {
	body {
		padding: 0 50px 50px;
		margin-left: 300px;
	}

	.site-header {
		position: fixed;
		left: 0;
		top: 0;
		width: 300px;
		z-index: 300;
		height: 100%;
		overflow: auto;
		overflow-x: hidden;
		-webkit-backface-visibility: hidden;
		-webkit-overflow-scrolling: touch;
		transition: .1s ease;
	}
	
	.admin-bar .site-header {
		top: 32px;
	}
	
	.site-header .main-navigation li {
		float: none;
	}
}

.inside-header {
	display: flex;
  flex: 1;
  flex-direction: column;
  align-items: center;
}

.site-branding,
.site-logo {
	order: 1;
}

.header-widget {
	order: 3;
}

.nav-float-right .inside-header .main-navigation {
	order: 2;
	float: none;
	margin-top: 30px;
	margin-bottom: 50px;
}

.nav-float-right .header-widget {
	float: none;
	top: auto;
	max-width: 100%;
}

#menu-social-sider li {
	display: inline-block;
	margin: 0 10px;
}

.dropdown-click .site-header .main-navigation ul ul {
    position: relative;
}

Then you'll need to remove the header widgets in "Appearance > Widgets", as they'll be pushing the navigation down.

Let me know if you need more info :)