What is a good add-on for WOW that makes your armor into armor sets that ways you can save invitory room and trade out armor without having to take each individual piece off

The best and easiest way is to use Equipment manager which is already in the game, just press the Esc button and go to interface,- features and enable it.
Then go to your char. info and then you will see a little button at the top from here it's easy just wear whatever gear you need and press save, name the set and pull the button to a free space on the actionbar.