Link Injection Removal..

All of a sudden I can see a “Google SEO” link at the bottom of the sidebar of my SEO & Technology blog. And it’s linking to some stupid site. I’ve no idea how that came there and I don’t know how to delete it now.

Can someone please let me know how I can delete that link or where has that linked been injected on my WordPress blog so that I can remove it from there?

Thanks a lot in advance.