kinokeo on "Remove custom taxonomy with htaccess"

I'm fairly new to Wordpress (previously a Joomla user) and htaccess isn't my strong point. I've downloaded a knowledgebase template that uses a custom taxonomy page type called "article" in the URL. So the URL reads:
http://www.mydomain.com/article/%postname%

I'm trying to remove "article" from the URL. The template publisher told me it wasn't possible to remove it, so I'm thinking the only option is to rewrite the URL using htaccess.

I've tried htaccess options from numerous posts in these forums, but none seem to work, I'm not sure why. For example I thought this would do it (snippet shown only of course):

# END WordPress
# RewriteRule ^article/(.+)/$ /$1 [R=301,L]

tried with and without this before the rewrite rule:

Options +FollowSymLinks
RewriteEngine on

The htaccess file is being recognised (fails when I put a garbage line in it) and but I feel like the rewrite rules aren't. There are other sites on the same server using rewrite rules successfully though so I don't think it's the server setup.

I've also tried numerous plugins. The only one that worked was Custom Permalinks (https://wordpress.org/plugins/custom-permalinks/), but this only allows rewriting of the URL one article at a time, which isn't an ideal way of doing it.

Any help on this is much appreciated...