Peter

Everything that your commenter writes should display literally. Back to plain text! No allowed tags, period.
<h4>Requirements</h4>
<ul>
<li>WordPress 2.5 or higher</li>
</ul>

Peter’s Literal Comments

All comments on your blog will be displayed as typed, without any allowed formatting.

wpsimpletools

Completely disables comments functionality from backend and frontend: 
* Hides existing comments 
* Close comments on the front-end 
* Disable support for comments, trackbacks and ping 
* Redirects any user trying to access comments page 
* Removes comments metabox from dashboard 
* Removes comments links from admin bar 
* Removes comments page in menu 
* Completely disables comments API

Disable Comments

The type of plugin I just love... does exactly what it says, no configuration necessary, source readable and understandable in minutes.

Simple, effective, no config ✅

Completely disables comments functionality from backend and frontend. Just install it, nothing to configure!

Peter’s Literal Comments vs Disable Comments