Follow blog feature uses the FriendConnect service provided by Google.
First, login in to Blogger.
Just go to following FriendConnect user page -
http://www.google.com/friendconnect/user/overview
After login, you will see the blogs you are following and sites you've joined with FriendConnect.
From there, click Settings on each blog (you will ask to enter your Google account password again) and then you can Stop following this site, or you can go to Sites I've joined section in the pop-up and quickly unfollow a lot of blogs.
