Making a tycoon only owner door working etc?

To answer your question, the ClickDetector.MouseClick event returns the player who clicked. You can simply use the code you wrote before to check if the player is equal to the ownerValue.

Personally, I'd recommend writing a function to make your code appear cleaner, as well as creating a variable for the humanoid, if you're going to use it again. Minor details, but not very important.

local Enabled = true
local Lasers = script.Parent.Lasers
local Button = script.Parent.Button
local OwnerValue = script.Parent.Parent.Parent.Values.OwnerValue


local function isOwner(player)
	if player == OwnerValue.Value then return true end
	return false
end

Button.ClickDetector.MouseClick:Connect(function(player)
	if isOwner(player) then
		if Enabled == true then
			Enabled = false
			Lasers.Transparency = 0.8
			Lasers.CanCollide = false
		else
			Lasers.Transparency = 0
			Lasers.CanCollide = true
			Enabled = true
		end
	end
end)

Lasers.Touched:Connect(function(Hit)
	local humanoid = Hit.Parent:FindFirstChild("Humanoid")
	local player = game.Players:GetPlayerFromCharacter(Hit.Parent)

	if humanoid and player then
		if isOwner(player) == false  and Enabled then
			humanoid.Health = 0
		end
	end
end)

https://developer.roblox.com/en-us/api-reference/event/ClickDetector/MouseClick