Resource Hints is a smart feature added to WordPress version 4.6. I think it might improve your site speed. But if you want to disable it, try this:
remove_action('wp_head', 'wp_resource_hints', 2);
References
Resource Hints is a smart feature added to WordPress version 4.6. I think it might improve your site speed. But if you want to disable it, try this:
remove_action('wp_head', 'wp_resource_hints', 2);
References