URLs leading to same content

[zerotrouble]

My site was running on a custom CMS then I decided to integrate it to wordpress since it provided a nice admin panel with ready to use plugins.

Now Google is indexing both old my CMS' and Wordpress' URLs.
xyz.com/articles/article/xyz-software-review is giving out same content as
xyz.com/xyz-software-review (without redirection).

I can't add noindex tag since the former type of pages don't even exist anymore.
I tried to remove them manually by requesting in Google webmaster panel but it was denied because that directory didn't have robot.txt

[DealerDan]

Just do 301 redirects.

[zerotrouble]

Just do 301 redirects.

Cheers mate
htaccess redirects just didn't come to my mind

[Michael Martinez]

If you have a lot of pages you might want to use a canonical meta tag instead.

ON EDIT: Actually, a directory-level redirect may be all you need.