What is the Church's stance on artificial life support? May a Catholic be removed from it?

If, by artificial life support, you mean something such as a ventilator, the use of such machines is not required when they are no longer therapeutic, and the person is certainly dying. Neither is it required to revive a person who is approaching death each time their heart stops. 
 
Allowing someone to die whom the Lord is certainly calling is morally very different from directly causing a person to die, which is what euthanasia advocates claim the right to do. 
 
One exception to the non‐required use of artificial means is that food and water, even if supplied by a tube, should still be administered to those who are approaching death. Only in rare cases, where the major organs of the body have already shut down and can no longer process food or fluids, can this treatment be discontinued.