Most likely I'll still be human. But if you can change my DNA and turn me into a newt, I'd be impressed.
Most likely, if you changed your DNA enough, while you would still bear a very close resemblance to other people, you would be rendered incapable of interbreeding with them, and hence by the usual working definition of species, you would no longer be human, or more preciesly you would no longer be a member of the species homo sapiens.