Big Bagel

That site’s using this premium theme:

https://www.woothemes.com/2009/12/optimize/

You can set a page/post as private (only admins and editors can view it) or password protected.

Content Visibility

If you’re looking for further options, such as making a post/page available only to specific users, there are plugins that might help. This one for example:

https://www.ads-software.com/extend/plugins/role-scoper/

Unless I’m mistaken, get_current_screen is only intended for use when showing an administration screen. Its function is to return the current screen’s hook suffix. If you want to explain what you’re trying to do, I (or someone) might be able to provide a good alternative.

Assuming I’m understanding correctly, you want to remove that bit of code on your static front page? Checking the current page with is_front_page like this should work:

<?php if ( ! is_front_page() ) { ?>
<div class="machines-banner"><a href="https://www.gotodesigns.co.uk/"><img src="<?php bloginfo('template_directory'); ?>/images/header-banner.png" title="home"</a></div>
<?php } ?>

$query_string should already contain the proper page parameter; try tossing it into your query parameters:

global $query_string;
query_posts( $query_string . '&post_type=site_updates&post_status=publish&posts_per_page=50' );

This page should help:

Resetting Your Password

There’s no built-in feature/option that would lock down a site like that. Can you give a link to the site?

To remove the problematic plugin, use an FTP client or a file viewer provided by your host to delete its folder (wp-content/plugins/buddypress-remove-avatars).

Now knowing want you’re looking to do, I would think using get_users or the WP_User_Query class would be easier.

Function Reference/get users
Class Reference/WP User Query

Something like this perhaps:

$args = array(
    'exclude' => array( 1 ),
    'who' => 'authors',
    'orderby' => 'display_name'
);

$authors = get_users( $args );

But if you really want to use a custom query, you’ll need to do as wspencer said and use ORDER BY. Since user names/display names aren’t kept in the posts table, you’ll have to find a way to use the users table. Might be as simple as ORDER BY $wpdb->posts.display_name, or you might have to look into joins. You could also run a separate query on the users table then only display users that have ID’s in both results. I’m not much of an SQL expert. ??

And just an aside, if you’re only grabbing data from a single column, you can also take a look at $wpdb->get_col:

https://codex.www.ads-software.com/Class_Reference/wpdb#SELECT_a_Column

I completely agree with using whatever works and pulling the adsense bit out while testing. ??

However, if the goal was to hide the adsense code on the front end from administrators, if ( ! is_admin() ) wouldn’t work. It would always evaluate as true for any front end page regardless of the role of the current user.

At the very least, whatever code cloudstr210 is now using resolved his problem, which is awesome sauce. ??

But, is_admin just checks if the request was for an administration page. From the inline documentation:

Does not inform on whether the user is an admin! Use capability checks to tell if the user should be accessing a section or not.

That’s just for the title and description that actually show in your website’s header. The things All in 1 SEO adds are in your site’s head; stuff that isn’t shown on your site but is used by browsers and search engines.

Your site-description div isn’t empty either; it’s displaying whatever you set “Tagline” to be in “Settings->General”. Currently, that seems to be “London Based Calligrapher Serving Calligraphy Nationally”. I would imaging if you weren’t using an image and hadn’t changed the code for the site-title div, you’d also see whatever you set “Site Title” to be.

…I just want to check if the user is admin…

Are you trying to check if an administration screen is being shown or if the current user is an administrator? If it’s the latter, then you want something like this:

if ( current_user_can( 'manage_options' ) ) {
    /* A user with admin privileges */
} else {
    /* A user without admin privileges */
}

Function Reference/current user can

What is the specific code you’re looking at in header.php?

Everything looks fine to me. I don’t see any duplicate or empty items in your site’s head.