How do you get rid of games on your gamer card that show the achievements? ?

My brother played a whole bunch of games on my 360 and sold them without completing any of the achievements. How do you get rid of those games?How do you get rid of games on your gamer card that show the achievements? ?You just delete the game history from the achievements screen..also if that doesn't work then you just go to memory and completly delete the game from you'r system.