domclic

EffortLess Disable All Comments allows you to disable comments, trackbacks, and avatars across your WordPress site or multisite network with a single checkbox. When enabled, it removes comment functionality, hides the Comments and Discussion menus, and blocks comment submissions. Uncheck to restore all features.
Features:
<pre><code>Disables comments and trackbacks for all post types.
Removes avatars site-wide.
Hides Comments and Discussion settings in the admin.
Blocks comment submissions via frontend, admin, and REST API.
Multisite support: applies settings network-wide.
Simple toggle to enable/disable.
</code></pre>

EffortLess Disable All Comments

Completely disables comments, trackbacks, and avatars site-wide or network-wide with a single toggle. Multisite compatible.

superann

This plugin filters the sitewide comments feed as well as individual post comment feeds.
Upon first-time installation and activation, all trackbacks will be removed from the default WordPress comments feeds. 
You can override this behavior on the options page and also use the comments or trackbacks only feeds described below.
URL for comments only feeds: add the variable “comments” to your feed query string.
<ul>
<li>http://mysite.com/comments/feed/?comments</li>
<li>http://mysite.com/?feed=rss2&withcomments=1&comments</li>
</ul>
URL for trackbacks only feeds: add the variable “trackbacks” to your feed query string.
<ul>
<li>http://mysite.com/comments/feed/?trackbacks</li>
<li>http://mysite.com/?feed=rss2&withcomments=1&trackbacks</li>
</ul>

Separate Feed Comments and Trackbacks

Remove trackbacks from your sitewide and individual post comment feeds, and/or have alternate feeds for comments or trackbacks only.

EffortLess Disable All Comments vs Separate Feed Comments and Trackbacks