What the Crystal for removing a quirk?

I couldn't figure this out so my Sims just by the Quirk be gone from the rewards store.

Type doesn't matter. It just needs to be rare.

http://www.carls-sims-4-guide.com/expansionpacks/getfamous/celestial-crystal-crown.php

Ha! My sim got a rare plumbite on his front porch during a lightning strike in a heavy downpour!

What helmet, where do you get it plz , i cant get rid of my sims qurks what ever there called . I have tried everything Help please