How to enable comments after installing this plugin for some time ?

I liked this plugin because it does the job. I have been using for some time on my site and now I want people to be able to comment on the site again. Even after disabling the plugin, deactivating or even uninstall the plugin, i still can’t get it working. I do not have any cache plugin installed. When people are trying to comment , it’s saying

You do not have permission for this request /wp-comments-post.php

Steps on how to enable comment back after using this plugin, would be much appreciated. Thanks.

https://www.ads-software.com/plugins/disable-comments/