Closing a comment thread is used to halt the discussion while allowing the current comments to remain visible. Closing comments can be done several ways:

Automatic closing

For your entire site you can specify how long you want comments to remain open after the thread has been created. You can find this option in your site's Settings > Moderation under Automatic Closing

Note: You can override this length for individual posts by going to the page directly and clicking the Settings gear to change the option.

Manually closing from the thread

If a single post needs to be closed, it can be done manually by going to the post, clicking the Settings gear and clicking Close Thread.

This method can also be used to reopen automatically closed threads.

Manually closing from the admin

Instead, you can still close an entire thread from the moderation admin by doing the following:

1. Locate one comment that belongs to a certain thread.
2. Expand the comment and click on "Show comments only from this thread"
3. This will do a search filter and display only comments from the same thread.
4. You'll now have the option to close the thread in the righthand sidebar.

Using the WordPress plugin?

Disqus will respect the Wordpress settings with regards to closing comment threads. If you're using Wordpress, you can close comments by disabling comments for each post, or setting an Automatic closing timer in your Wordpress discussion settings.