Leave them alone. They are blind, and they lead the blind. But if the blind are in charge of the blind, both will fall into the pit.
Other versions
King James Version
Let them alone: they be blind leaders of the blind. And if the blind lead the blind, both shall fall into the ditch.English Standard Version
Let them alone; they are blind guides. And if the blind lead the blind, both will fall into a pit."New International Version
Leave them; they are blind guides. If a blind man leads a blind man, both will fall into a pit."