Quick Answer: File the Overlay down until you reach the unharmed natural nail beneath.
Long Answer: The Personal Salon Home Nail Care System was designed to add to the structure of your nail without damaging the natural nail beneath. Since Personal Salon Overlay nails add to the structure of your natural nail using an organic protein bond (the strongest bond in organic chemistry, called a "double covalent bond"), chemicals won't easily remove the bond. That is good, because it means your nails aren't going to easily come off in most situations. Thus, to remove the nails, you simply file the Overlay down until you reach your unharmed natural nail beneath. Though Personal Salon Overlays are strong and durable, they can be filed down relatively easily.