How do I deindex url parameters

[BT2009]

Google indexed a bunch of our URL  parameters. I'm worried about duplicate content. I used the URL parameter tool in webmaster to set it so future parameters don't get indexed. What can I do to remove the ones that have already been indexed? For example, Site.com/products and site.com/products?campaign=email have both been indexed as separate pages even though they are the same page. If I use a no index I'm worried about de indexing the product page. What can I do to just deindexed the URL parameter version?

Thank you!

[BT2009]

Thanks everyone this is really helpful!

[DirkC]

As Linda mentioned, adding a canonical url to the version without parameter is the best solution as it gives you control on which pages should be in the index.

For the sake of completeness - in webmaster tools you also have the option to tell the Google bot how it should deal with parameters (under Crawl > URL parameters). Note however that Google itself doesn't really recommend using this option.

rgds

Dirk

[PatrickDelehanty]

Hey there!

I would also add that you can look at the Robots.txt Specifications resource from Google for tips.

Hope this helps as well!

[Linda-Vassily]

Put a canonical tag on site.com/products to itself and the parameter versions will go away. (They eventually will anyway--duplicate content does not cause a penalty, it just causes duplicate versions to not be indexed, which is what you want anyway.)