Facebook changes so often that it's hard to keep up. You may have seen my previous tutorial on this, but almost seven months later, that tutorial is obsolete.
In some ways it is now a little easier to unlike multiple pages. There is also a nice little added feature that wasn't there in my previous tutorial. You can now easily hide pages from your News Feed if a page posts too much but you still want to support them with a "Like" or be able to visit their page at your leisure.
Click on the More tab and then scroll down to click Likes
The default setting is to add more pages. Click the "Add Likes" button and it will change from a plus sign to add to a check mark. The check mark shows the pages that you currently like.
You will then see tabs on the top which are the sections where the pages you like are. Click each section to unlike or hide pages by hovering over the picture of the page.
This will bring up the "Liked" button. Hover over that and you will then get a menu where you can either unlike or hide the page from your News Feed.
Here is an alternate method pointed out to me by a reader:
Go to your timeline and in the righthand column you will see a list of years. Click on a year.
It will open up items from that period like photos, posts, and it will also bring up your likes. Click on the number.
A box will open up with all of the pages that you liked in that period. You can click the box to unlike the page or hover over it to bring up a menu where you can hide it from your News Feed, add the page to an interest list, or unlike the page.