There should be an option to clear the document completely. When you share the pdf it will not be a 'used' book.It'll be clean and new.
Suppose a professor prepares theclass witha ebook and then he needs to send the book to his students. he'll like to send it clean, without marks or highlights of the answers. Its like sharing a new book. nobody wants to read a book already lined by someone else. better share it clean.
Are you suggesting for this idea: http://feedback.xodo.com/forums/241992-suggest-a-new-feature/suggestions/6995687-delete-all-annotations
If so, please upvote that. Thanks!