removeLayer.lua

local length = 4
local width = 4
local ignore = "minecraft:cobblestone"

function digForward(  )
    while turtle.forward() == false do
        turtle.dig()
        turtle.attack()
    end
end

function cleanInv( slot )

    if turtle.getItemCount(slot) > 1 then
        local data = turtle.getItemDetail(slot)
        if data.name == ignore then
            turtle.select(slot)
            turtle.drop(turtle.getItemCount() - 1)
        end
    end
end

local lastTurnRigth = false
length = length - 1

for i=1,width do
    for i=1,length do
        digForward()
    end
    cleanInv(1)

    if lastTurnRigth == false then
        lastTurnRigth = true
        turtle.turnRight()
        digForward()
        turtle.turnRight()

    else
        if lastTurnRigth == true then
            lastTurnRigth = false
            turtle.turnLeft()
            digForward()
            turtle.turnLeft()
        end
    end
end





if lastTurnRigth == false then
    lastTurnRigth = true
    turtle.turnRight()
else
    if lastTurnRigth == true then
        lastTurnRigth = false
        turtle.turnLeft()
    end
end