There are plugins to disable comments, we have tested and tried many to see how they work and based on our experience “Disable Comments – Remove Comments & Stop Spam [Multi-Site Support]” is the best of the many we have tested. The plugin gives you two options:
1. Disable comments on any page, post or media.
2. Choose based on roles, for let’s say an administrator will be able to see the comments as well as the author and the editor, but the contributor and the subscriber won’t be able to see them.
As well as disabling comments it can permanently delete them. The deleting part of the plugin works almost the same way as the comments disabling feature, as we said in the disabling part of the plugin you can choose which roles can see them but in the deleting part, you cannot. You can set where the comments need to be deleted, or the type of comment that needs to be deleted, and for both, you can select to either disable spam comments or permanently delete them.
We recommend the use of this plugin as it is easy to use and is nice to have it when you’d like to restrict comments on your website.