Limiting ROBLOX's CoreGui Inventory, how?

Hello all, me again! So I've recently decided to create a form of 'Battle Royale' for my game, and I've been wondering, how could you limit ROBLOX's CoreGui Inventory and is it possible? I've done some research regarding it, and instead of having to create a whole new system, I thought why not just edit the preset one? So, any and all help to answer this question is awesome! Thanks all!

You can't really edit roblox's Coregui, its used for Things like Menu, chat, leaderboard, no scripts have or should have permission level to edit (only game scripts) , however, you can disable some like leaderboard, chat, topbar, inventory, using predefined functions, heres an example of what you can do:

wait()
pcall(function()
	local starterGui = game:GetService('StarterGui')
	starterGui:SetCore("TopbarEnabled", false)
end) -- this disables the annoying top bar so you can fill all screen space for your GUIs