Using StarterGui:SetCoreGuiEnabled(“Chat”,false) does not remove it, and I don’t think there is any other way to remove it.
The button is just so ugly when you’re using a custom chat UI, so why not be able to remove it and replace it with your own?
Because it’d probably be difficult for mobile users to access a custom made chat HUD; saying from experience since I can barely use Gui Objects on my iPhone when in-game.