After you click the generate Book of Authority button in the Microsoft Word ribbon, a window will pop up with a list of all of the references used in your document. Beside each reference is the option to "include in full" or "exclude."
Simply select which references you want to include or exclude by clicking on the circle beside either option. For whatever you select exclude, that reference will not be included in the Book of Authority. Selecting include in full will show the full case text of that reference in the Book of Authority.