Removing tools from players character or backpack?

Because the callback function to MouseButton1Down passes two arguments: integer x and integer y, which represent the coordinates of the mouse. You took these arguments with player and weapons in your onClick function. This is unnecessary, since you already have a reference to the local player and to the weapons table.

You're also passing the weapons table to findFirstChild, which is just going to return nil. I assume you want to iterate the list of weapons to see if they exist inside the player's Backpack or Character, so for that you should use a (numeric) for loop.

-- ... code from above

script.Parent.MouseButton1Down:Connect(function()
    -- Create variables for easier reference
    local character = player.Character 
    local backpack = plater.Backpack

    -- Iterate weapons list via index
    for n = 1, #weapons do
        local weaponName = weapons[n]

        -- Find weapon in container
        local charWeapon = character:FindFirstChild(weaponName)
        local backWeapon = backpack:FindFirstChild(weaponName)

        -- Remove them if they exist.
        if charWeapon then charWeapon:Destroy() end
        if backWeapon then backWeapon:Destroy() end
    end
end)

You should also use Connect over connect (same goes for disconnect, and other event signal methods). ROBLOX has deprecated the use of them and they've since been replaced. Same goes for findFirstChild, which should be FindFirstChild.