When you create or modify several styles that you want to use over and over again, you can save the whole group as a single Quick Style set. That way, you can keep all the styles you use in one place and, if you want to, you can remove the styles that you never use.
Create and/or modify the styles you want in your set, and make sure they’re added to the Quick Style gallery.
Right-click any styles that you don’t want in your style set, and choose Remove From Quick Style Gallery.
Click Change Styles ...