Anybody know how to completely take a game off the harddrive?

[Rubiks14]

well i think i figured out y my call of duty 2 keeps on starting me over...for some reason when i started a new game i could pick like one of the levels from the middle of the game and play it from there (didn't think anything of it until like now)....my brother has an account on my xbox and his works just fine (he has to start from the beggining)...anyway i've tried to delete it off my harddrive from the memory area but for some reason it is still screwed up and it still has call of duty on my harddrive (it says i have a save on there and it keeps my accomplishments) . anybody know how i can get it off?

[DeadOneWalking]

Format the HDD.

[Rubiks14]

yea i would have done that but i didn't feel like having to put my xbox live account on there again because my dad would have b!tched @ me if i called him to get like his email password again and stuff like that. but i finally got it off (not sure how though)