Board Thread:Support Requests - Community Management/@comment-6475116-20130215022218/@comment-1999071-20130215030659

You should be able to remove the category by hovering your mouse over the category section in the right rail while you are editing the page. There should be a small image of a trashcan that will pop up. Click it, and the Category will be removed.

Alternatively, you could edit in source mode and simply add : in front of Category and it should fix it.