Someone else's stats on my Waypoint Career

I just logged onto halowaypoint for the first time, and I noticed that in my Waypoint Career it says I have played a total of 276 games, got 1628 kills, with a .67 k/d.

The thing is I have never played a Halo game before. I did a quick check on bungie and I found this under Halo 2:

I guess when I signed up for Xbox Live last year I got an old tag that was purged. How do I get rid of this other person’s stats that is now linked to my account?