This theme consists of support for Disqus Comment. WordPress comment is the default comment system in this theme. If you want to replace WordPress Default
comment System then install Disqus Comment plugin. After Installing plugin, Disqus comment system will override default comment.
To Download Disqus comment go to https://wordpress.org/plugins/disqus-comment-system/
Further Tutorial
https://disqus.com/admin/wordpress/
http://www.wpbeginner.com/plugins/how-to-add-disqus-comment-system-in-wordpress/