Can I post an article and not allow replies just for that post only?

Hi Chris Banks, yes you can turn off replies on a single post.

If you are creating the post in the Admin console: while you are in the editor, expand Replies in the side column and uncheck Allow replies.

If the post is already published: click the gear icon on the post and select Close replies.

 Either way, members and guests will no longer see the option to add a reply on that post.

One thing to note: if you are an Admin/Moderator, you will still see the "Reply to topic" option, since admins and mods can always reply regardless of the setting. You can confirm the status by opening the gear menu. If you see Open Replies listed, that means replies are currently closed, and you can use that same option to reopen them later if you change your mind.