Per Søderlind

On posts where comments are closed, the plugin will remove the text ‘Comments are closed.’ The plugin supports any languages/text domain, and will remove the text from themes and plugins.
Prerequisite: Since the plugin is <a href="https://codex.wordpress.org/Plugin_API/Filter_Reference/gettext" rel="nofollow ugc">filtering gettext</a>, your theme/plugin must be <a href="http://wp.smashingmagazine.com/2011/12/29/internationalizing-localizing-wordpress-theme/" rel="nofollow ugc">localized</a>.
View the plugin source code at the <a href="http://soderlind.no/archives/2012/01/11/wordpress-plugin-remove-comments-are-closed/" rel="nofollow ugc">plugin home page</a>

Remove "Comments are closed"

Remove the "Comments are closed" text from posts.

Amitpal Singh

On posts where comments are closed, the plugin will remove the text ‘Comments are closed.’ The plugin supports any languages/text domain, and will remove the text from themes and plugins.

Hide "Comments are closed"

Working Nice

Hide the "Comments are closed" text from posts.

Remove "Comments are closed" vs Hide "Comments are closed"