I would like to discontinue or change someone I was following. Not sure how to do this?
On your home page, under the "Activity Stream" section on the left, it should have "Following x" where x is the number of people you are following.
Click this text, it will pop up a window. There will be listed everyone that you follow, and green "Following" buttons to the right.
Click the big green "Following" buttons that have the check mark. This will change it to " + Follow" and you will no longer be following that person.