A family of Microsoft word processing software products for creating web, email, and print documents.
To get rid of styles that have been added to a template, you can use the Organizer dialog box. In the Manage Styles dialog box, click Import/Export to display the Organizer. The image below shows a custom style called "Test" which I added to the Normal template (see how it is listed under "In Normal.dotm" on the right):
Click to select "Test" and then click Delete.
Later, if/when you are prompted to save the changes to the template, choose to do so.
Note that deleting a style from a template only prevents it from being present in new documents based on that template. If existing documents already have the style, you have deal with that one document at a time.
Also, remember that you can only delete custom styles, not the built-in ones.