Example follows.
http://howto.cnet.com/8301-11310_39-57379574-285/how-to-delete-unwanted-ios-apps-from-itunes/
I have several hundred apps which I bought or were free. I would like to get rid of some of these apps because I don't use them. I can not find a way to delete them from iTunes.
I've tried selecting and hitting delete but nothing happens.

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