First, you need to be clear whether you do have a lot of styles, or whether
you are seeing direct formatting that has been applied on top of your
styles. The Tools > Options > Edit "Keep track of formatting" option will
show formatting *and* styles if it is checked, and styles only if it is
unchecked.
Then, using the Styles and Formatting pane with the "Keep track of
formatting" setting On, you can work through the styles and formatting in
the document to tidy up. The dropdown menu against each entry will show (for
a style) whether it is use or not and allow you to delete the style if you
wish. It will also allow you to select all instances of particular
formatting, so you can apply one of your standard styles.
For more information, see:
http://www.shaunakelly.com/word/sfpane/StylesAndFormattingPane.html
