how do you teleport a player ??

You tried to index "game.Workspace.Player" but likely "Player" is not a player in your game. Look at the output.

The simplest way to teleport is by cframing the torso. If you want to do it on 'X' then here is how.

game:GetService('UserInputService').InputBegan:connect(function(input,gpe)
    if (not gpe) and input.KeyCode == Enum.KeyCode.X then
        game.Players.LocalPlayer.Character.Torso.CFrame = CFrame.new(Vector3.new(-2.7, -151.9, -580.5))
    end
end)

Like cabbler said, the problem likely is you tried to index 'Player' as though it were an actual Model/Character inside the workspace. To add upon what he said, it's better to use HumanoidRootPart to ensure compatibility with R15. Here's an updated version of your code:

game:GetService("UserInputService").InputBegan:connect(function(input, guiStatus)
    if not guiStatus and input.KeyCode == Enum.KeyCode.X then
        game:GetService("Players").LocalPlayer.Character.HumanoidRootPart.CFrame = CFrame.new(Vector3.new(-2.7, -151.9, -580.5))
    end
end)

if script.Parent.TP.Enabled == true then
    function Pressx(key)
       if(key == "x") then

        game.Players.LocalPlayer.Character.Torso.CFrame = Vector3.new(0, 0, 0)

       end
    end
end