clearout

function clearrowf()
 for a=1,8 do
  turtle.dig()
  turtle.forward()
 end
 turtle.turnRight()
 turtle.forward()
 turtle.turnRight()
end
function clearrowb()
 for b=1,8 do
  turtle.dig()
  turtle.forward()
 end
 turtle.turnLeft()
 turtle.forward()
 turtle.turnLeft()
end
function clearfloor()
 for c = 1,4 do
  clearrowf()
  clearrowb()
 end
end
function onedown()
 turtle.turnLeft()
 for e =1,8 do
  turtle.forward()
 end
 turtle.turnRight()
 turtle.digDown(down)
 turtle.down()
end
function cleardown()
for d = 1,18 do
 clearfloor()
 onedown()
 end
end

cleardown()