I replaced the existing title code with <?php wp_title(''); ?> in the header.php to get rid of the double title issue caused by my Yoast SEO plugin but it did not work. Instead of taking out the extra site name, it instead replaced everthing with the page's URL. I found a work around by selecting the 'Force rewrite title' option in Yoast's Title Settings. It solved the issue on all the posts and pages except the homepage where it shows the site name but not the title (- Website Design Boss). My website is www.websitedesignboss.com. How can I add a meta title to my homepage?
That's weird. I tried pasting the above code in again and now it's working. Must have been corrected with a recent plugin update.