Liked items are for advertisers, they’re not for you. In Facebook’s estimation, you don’t need to remove a page you no longer like, because you are never going to visit it anyway.
Jeffrey Zeldman: Managing Facebook Like. Or not.
I stripped my profile to the bone and still cringe when I have to wade into the steaming pile that is The Internet™ to most of my peers. Took me 20 minutes to find out how to remove applications, which can do a lot more than rot in a ghetto full of ads.