You can show or hide comments on posts globally by navigating to the Discussion Settings.
- Simply, navigate via WordPress Dashboard to the Settings » Discussion,
- Under the Default article settings check or uncheck the Allow people to post comments on new article box,
- Click the Save Changes button.
These settings can be overwritten for individuals articles.
- In the new WordPress 5.0 editor check or uncheck the Allow Comments metabox under the Discussion group options.
- Click the Update button.
This feature is supported in Classic editor as well.