DeveloperWil

Completely disables the XML-RPC API which was introduced in WordPress 3.5 and above which lets remote clients post, upload and edit content.
Notes: 
If you are using the WordPress smart phone app or the Jetpack plugin, please note that they need this service enabled.
If you activate this plugin your WordPress phone app will not be able to connect to your site and Jetpack will not be able to connect to wordpress.com where site visitor data (and other stuff) is stored.
Other plugins and services that use the XML-RPC API will also not function properly.
<h4>Plugin Page</h4>
<a href="https://zeropointdevelopment.com/wordpress-plugins/deactivate-xml-rpc-service-wordpress-plugin/" title="Deactivate XML-RPC Service WordPress Plugin" rel="nofollow ugc">Deactivate XML-RPC</a>

Deactivate XML-RPC Service

Disables the XMP-RPC API service introduced in WordPress 3.5 and above.

Mark-k

With WordPress version 3.5 remote publishing via XML-RPC became permanently active. This plugin simulates the functionality in versions 3.4 and before. Once active, XML-RPC functioning is disabled, and it can be enabled or disabled again in the “Settings” >> “Writing” admin page.

Control XML-RPC publishing

Control remote publishing with XML-RPC from the writing settings page.

Deactivate XML-RPC Service vs Control XML-RPC publishing