How to turn off comments in WordPress
The default configuration allows users to post comments on your site.
If you wish to disable the comment function, log in to your admin panel and go to Settings menu > Discussion
and uncheck the box that says Allow people to post comments on new articles then click on the Save Changes button.
This will disable the function for all new posts/articles.
If you wish to disable comments for existing posts, go to the Posts menu and click the box that says the old posts,
select Edit from the Bulk Actions drop-down menu and click the Apply button.
Select Do not allow from the Comments drop-down menu and click the Update button.