Xbox 360 de-friending someone

How would I go about doing this? I can't find anything useful in the Xbox 360's wonderfully informative menus.

I'm not sure how to do this on the console, but I know that you can remove friends from xbox.com. Log in using the Windows Live ID associated with your GamerTag, and go to the Friends Center. There is a "Remove" button by each person on your Friends List that you can use to remove them.

When you select a friend's gamertag and the menu pops up ("Invite to Party", etc.), one of the options near the bottom is "Remove Friend":

_{(Source: http://support.xbox.com/xbox-live/social/chat-managing-friends)}