The document inspector is located in the prepare menu which can be can found by clicking on the Office Button (Alt+F, E, I). When launching the inspector, if you haven't saved your file before making the most recent changes, you will be prompted to do so. It's not required that you save; however, the reason we provide this dialogue is because once you run the inspector, and choose to remove certain components of a document, they are GONE.

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So as the product manager for Word, I spend a ton of time producing content. This often has to go through numerous review cycles with legal, our PM's, and others. After numerous rounds of markups and review, what started as a regular old document is often littered with comments, revisions, and markups galore. In addition, because I created the document, my personal information is available to any curious reader. Once I am ready to publish my content I would run the inspector. Because I don't want readers seeing all the comments or reading my personal information, I would search for, and remove it. I probably also don't want people seeing hidden text so I would get rid of that too. I would want to hold onto things like headers and watermarks because I use them in my documents.

[http://blogs.msdn.com/microsoft_office_word/ archive/2007/03/15/the-document-inspector.aspx]