Well in the uk you need to do a deed pole for name change then you can make up I'd on that name apply for credit get legit I'd and slowly move on, but if you have legal problems and police have your finger prints or DNA then if you get arrested all your preivous details will come up.
In the USA I think one way would be to take over a real legit person I'd like a bum or a person who does not use his name for credit and other lifely matters.(if you can find one) them make new ids on that name and live as that person this is one such idea I'm sure there must be others, but the main point for a total I'd change would be if Law enforcement has no record of you,then it is possible for a total new identification.
Anyway good luck