Here is an option to disable comments for boards or posts of your choice. This option will disable users, members and admins from adding any comments to the posts in the board or the respective posts, you had disabled comments.
You can choose to disable comments while creating a bucket or edit the bucket settings after creation. All you need to do is check the box.
You can disable comments to a single posts from the options dropdown in the post show page.
To revert this you can uncheck the disable comments box from the bucket settings or click on enable comments from the post settings.