So, my main issue is that I have no freaking clue on how to make a script where a GUI pops up on your screen.
You click the GUI, and it equips your helmet but hides your hair. No clue how to do that in the slightest. Which is why I'm here, please respond, and have a nice day.

3 comments
Check the wiki articles about text/image buttons and accesories. You will also need to use remote events, so maybe give the article covering that topic a look aswell.
You can set the MeshId of the Mesh ID to nothing to "remove" the hat when the button is clicked.
Or just remove the hat using :Destroy() or :Remove()