UPDATE (November 2011)
It appears Facebook’s interface has changed again (big surprise!), so this no longer works. I don’t have any missing pages with which I can test a new solution, but for pages which still exist, the unlike link is still available when viewing the page.
FIVE SIMPLE STEPS
- Login to Facebook and visit your profile.
- Click the “Edit Profile” button (top-right).
- Click “Activities and Interests” (left sidebar).
- If you don’t see the page you want to “unlike,” click “Show Other Pages” (main column, after Interests).
- Click the appropriate “x” (Activities and Interest blocks) or “Remove Page” button (Show Other Pages dialog).
ACKNOWLEDGEMENTS
How Can We Unlike All pages?. Devers, Chris. 3 May 2010.