My shared items feed was private, and I want to make it public, so I decided to remove all it contains.
How can I do this?
Unfortunately, there still isn't a way to bulk unshare items in Google Reader.
The solution offered is to use keyboard shortcuts to make it a bit easier.
While viewing your shared items
I expect you could use something like AutoHotkey to automate this further.
Note: Since the Google Reader change to utilize Google+, this is no longer possible.