Help needed! About Tag and category!

I have a Wordpress blog but has independent domain. I write something about our products and post there, then use some keywords link to our site. However, several days ago, I found that there are too much links from my blog link to our site, and most of them are related with tag or category, so is there some way to make these links about tag or category nofollow or don't link to our site?

Any answer will be appreciated! Thank you very very much!

If you are using Wordpress SEO by Yoast, you can make use of the sitemap and exclude 'tag' taxonomy. Alternatively you can go to webmaster tools section and remove the links manually.