I suppose that would depend on the context. If authorities gathered up all available copies of a book (or group of books) and burned them to prevent their distribution -- then yes. If the members of a group such as a church or social club collected copies of a book or group of books that they had legally obtained and burned them as a symbolic act of protest against content they deemed objectionable, then that would not be censorship.
"If authorities gathered up all available copies of a book (or group of books) and burned them to prevent their distribution -- then yes."
I agree with the above.
Then by your definition I think making Karen Hughes speech unavailable for distribution, all copies of it, was censorship. Especially considering that such a speech is in the normal course available.