One of the easiest way to remove certain features from WordPress is to create a function and use them up with WordPress Action Hook. Most of these hooks can be used from your theme's functions.php file. Let's see one such demonstration.
By default Really Simple Discovery (RSD) link and meta tag gets generated by the WordPress itself to make our life easier. In case if you want to use any client software to write, edit any post, RSD tags are essential. However, if you are not using such software, you can easily remove this meta tag from your site.
There are ways to remove it from your theme's header section. However, the simplest way to do that is to add the following line on your theme's functions.php file.
// removing RSD link remove_action('wp_head','rsd_link');
Once done, simply update the page. Now, go back to the front end of your site and refresh it. Take a look at the source code of your site. Your shouldn't have the RSD link anymore.