Disable Yoast's hidden declaration of love in the source code
I've always liked the Yoast SEO plugin and it's one of the only few third-party/free plugins I include in the sites I develop. But over time, more and more unnecessary stuff has been added and one of those things is the hidden declaration of love that gets added in the source code ""This site is optimized with the Yoast WordPress SEO plugin"
Use the following function to remove:
add_filter( 'wpseo_debug_markers', '__return_false' );