A way to quickly un-like a lot of pages and things, cleaning up your profile, and also cleaning up your news feed.
Drag this green bookmarklet to your bookmarks in the toolbar.
Go to your profile, then to your list of Likes, under the More menu.
Wait for the page to load up. This takes several seconds - watch the spinner in the tab.
Click the bookmarklet.
Wait around 10 seconds for the "liked" to change back to "like".
Congratulations, a page of "likes" have been removed.
Reload the page to do another batch.