The skin is "sanded" to remove the epidermis and dermis
along with the ink. This is the oldest methods of tattoo removal
going back more than 5000 years. These method was based primarily
on abrasion with a metal tool. When used in combination with salt
as a grit it is sometimes called salabrasion. When the skin is
frozen beforehand, to reduce bleeding and pain, it is refered
to as cryosurgery.
This is a painful procedure that can easily lead to scarring
or infection. In general it is not practiced nor recommended nowadays.