On all my site pages it displays the page they are already on under the navigation bar e.g 'Home' as in the photo. How can I not show this? Thanks.
Your theme (or child theme) is likely using
page.php as the default page template. This file likely contains a call to the WP function
the_title() which is generating the visible page title.
Multiple options to modify this. Assuming you are using a theme which will have updates available, your changes should be made using the Child Theme approach in WordPress. https://codex.wordpress.org/Child_Themes. This will ensure your changes survive an update to the parent theme.
Assuming you never want the page title to show, simply removing the call to
the_title() and any associated markup (heading tags, etc) will eliminate this.