Extra Theme – How to remove the Previous and Next navigation on all posts

The following css worked for me:

body.single-post .post-nav {
    display: none;
}

You paste the above CSS at the following location: navigate to back-end admin | Extra | Theme Options | General | Custom CSS

I obtained the CSS from the following page:

https://divi.help/threads/how-to-remove-share-bar-and-previous-post-columns.145