What happens when i delete my saved file for modern warfare 2?

my dumb *** little cousin is always coming over to my house and trying to act all cool by being a hacker on modern warfare 2. he did a lot of crap to my game like tenth prestige/ aim bots / god modes/ he even got "eleventh prestige". i want to actually play the game the way it was meant to. if i was to delete my saved files for modern warfare 2, would the game go back to the original form so i could start off at level one?