Administrators and users that have the required permissions (see a list of all the plugin’s permissions here) have access to a new submenu within the built-in Comments menu item. The submenu is aptly named Internal Comments.
The submenu redirects to a page containing a stripped-down version of the default comments list table. All non-supported features have been removed/disabled to reduce confusion. It should look like this:
This view allows people with the proper permissions to edit or delete existing internal comments, and even to reply to existing ones.