How would I kill a person when they dont have a gamepass touching a door?

I am trying to kill a humanoid if they do not have a gamepass, but I cannot seem to find how to get a player id via humanoid

If you're trying to get the Player ID (I'm assuming user id?) I would suggest using GetPlayerFromCharacter

It's pretty simple, first you start with game.Players followed by :GetPlayerFromCharacter then followed by parenthesis that are stored with the character. An example script would be:

local part = script.Parent

part.Touched:connect(function(hit)
	if hit.Parent:FindFirstChild("Humanoid") then
		local player = game.Players:GetPlayerFromCharacter(hit.Parent)
	end
end)

Once you have the player defined, find the ID by using player.UserId

You can use Touched event

Place this in the door:

local Door = script.Parent

local RequiredId = 9999 -- your gamepass id
local Kill = true -- determines if the door can kill

function TOUCHED(hit)
	if hit then 
		if game:GetService("Players"):FindFirstChild(hit.Parent.Name) then -- check if player
local player = game:GetService("Players"):FindFirstChild(hit.Parent.Name)
			if player:IsA("Player") and CHECK_ACCESS(player) then 
				--code

			elseif Kill then 
				player.Character:BreakJoints()
			end
		end
	end
end

function CHECK_ACCESS(player)
	if game:GetService("GamepassService"):PlayerHasPass(player, RequiredId) then 
		return true 
	else
		return false 
	end
end

Door.Touched:connect(TOUCHED)