Here is how you can delete an article that you no longer need and how to restore it in case it was not intentional.
First, navigate to the articles listing page of your help center dashboard.
There you can see that each article has several options available as icon buttons with the trash bin being the first one.
Find the article you would like to delete and click on that icon.
Once you delete an article, it goes to the Recycle Bin of your help center. If at some point you decide you would like to get that article back, you can do so by navigating to the Recycle Bin that is available at the trash bin icon in the main dashboard menu.
Once you open the Recycle Bin, you will find all deleted articles there.
Find the one you want to restore and click on the icon of a trash bin with an arrow pointing up. This would put your article straight back to your help center.
And this is how you delete and article and restore it if you make up your mind at some point.