By default WP supports oEmbed which allows users to add media content (videos, music, images etc.) within their post very easily. WP has pretty good documentation of this service which could be particularly useful for certain users.
However, I personally do not want to use this service as I barely add contents from third party web sites. oEmbed adds two different tag line on your site's header section. Removing them seems to disabled this service automatically. These tags looks something like this.
Now, in order to remove them, you just simply need to copy and paste the following snippet on your current theme's functions.php page and you are good to go.
<link rel="alternate" type="application/json oembed" href="" /> <link rel="alternate" type="text/xml oembed" href="" />
<?php // removes oembed discorvery link remove_action('wp_head','wp_oembed_add_discovery_links', 10 ); remove_action('wp_head','wp_oembed_add_host_js'); ?>
Do not forget to update your functions.php page. Go to the front-end of your site and refresh your page. You shouldn't be seeing the tags on your site's header section anymore. Hope that helps.