The Yoast meta box sits just below the main editor. To demote it, aka, reduce its priority, just add this anonymous function to your theme (or better still, a custom plugin):
add_filter( 'wpseo_metabox_prio', '__return_false' );
Or, you can use the more commonly quoted approach of explicitly stating the meta box’s positional priority to ‘low’:
add_filter( 'wpseo_metabox_prio', 'filter_wpseo_metabox_prio' );
function filter_wpseo_metabox_prio() {
return 'low';
});
With namespace:
add_filter( 'wpseo_metabox_prio', __NAMESPACE__.'\\filter_wpseo_metabox_prio' );
function filter_wpseo_metabox_prio() {
return 'low';
}
And if you’re a fan of one-liners set the priority with an anonymous function:
add_filter( 'wpseo_metabox_prio', function() {return 'low';} );