My player list is not removing players, why is that?

I am creating a GUI playerlist of buttons with each player on each button. However, when a player leaves, their button is not removed and just stays there.

Here are the scripts:

Client:

onPlayer = game.ReplicatedStorage.OnPlayer
x = 0
y = 0.178
frame = script.Parent
children = frame:GetChildren()
buttonSize = UDim2.new(1, 0, 0.178, 0)

local function button(name, xPos, yPos, parent, textColor, backgroundColor)
	local button = Instance.new("TextButton")
	button.Parent = parent
	button.Text = name
	button.Position = UDim2.new(xPos, 0, yPos, 0)
	button.TextScaled = true
	button.Name = name
	button.Size = buttonSize
	button.BackgroundColor3 = backgroundColor
end

local function getIndex(tab, elem)
	for i = 1, #tab do
		if tab[i] == elem then
			return i
		end
	end
	
	return -1
end

local function decreaseCanvas()
	y = y - 0.178
	frame.CanvasSize = UDim2.new(0, 0, y, 0)
end

local function destroyAllButtons()
	for i = 1, #children do
		if children[i].ClassName == "TextButton" then
			children[i]:Destroy()
		end
	end
end

local function createList()
	x = 0
	y = 0.178
	frame.CanvasSize = UDim2.new(0, 0, 0, 0)
	local players = game.Players:GetPlayers()
	
	for i = 1, #players do
		button(players[i].Name, x, y, script.Parent, Color3.fromRGB(0, 0, 0), Color3.fromRGB(255, 255, 255))
		y = y + 0.178
		frame.CanvasSize = UDim2.new(0, 0, y, 0)
	end
end

onPlayer.OnClientEvent:Connect(function()
	destroyAllButtons()
	createList()
end)

Server:

onPlayer = game.ReplicatedStorage.OnPlayer

game.Players.PlayerAdded:Connect(function(player) 
	onPlayer:FireAllClients() 
end)

game.Players.PlayerRemoving:Connect(function(player)
	onPlayer:FireAllClients()
end)

The problem is you're firing the same Remote Event for both the PlayerAdded and PlayerRemoving events without parameters, to change this, simply add a parameter or use two different Remote Events.