How to Reset Your Stats in Modern Warfare 2
It is always possible to reset stats by deleting the files mentioned below. Rank up in an online match to make the reset permanent.

To reset (deleted) your stats without the help of EA, make sure MW2 is not running and navigate to (default):
-C:\Program Files\Steam\SteamApps\common\call of duty modern warfare 2\players …and delete all .stat files.

Then navigate to (default):
-C:\Program Files\Steam\userdata\(some numbered folder)\(some numbered folder)\remote\
-And delete the two files residing in that folder. These file names will differ between each player / Steam account.