WordPress: Disable Comments
How to completely disable comments using functions.php
The code below will completely disable any commenting and trackback features in WordPress. It is in response to the usual issue whereby you think comments have been completely turned-off only to get a notification that there are a new comments waiting moderation.
This code won’t turn off any “This post has X comments” or front-end code that displays comments that may be in your theme. Instead it removes the ability for comments to be added/stored against posts. To remove front-end comment boxes and listings you’ll need to change your individual templates
Simply copy and paste into your functions.php file in your WordPress theme folder.