Yes, resetting your rank is a glitch. I don't think you can by deleting then reinstalling the updates. But you can make a brand new silver account and SPG the rank 1 onto your main account if you need to.
i'm not 100% on this but i've heard from a few people that your rank isn't serversided. It's suposedly stored on your account (the xp level) and the update tells the xbox how to interpret it. Otherwise you'd see no rank. Thats why deleteting your update won't work. When I get home tonight (at school atm) i'll look into this and post anything I find. but for now justdo what twisted does
The new number rank system is just a cover up of your old rank FYI and deleting the patch and then playing without the patch will get rid of your rank and xp. After when you are in an offline game just quit to the lobby and connect to xbox live and voila! You are a rank one will all of your hardwork still there. It will not get rid of your leaderboard ranks. Me and my friends do this all the time because they are ranked high on the leaderboards like top 10 thousand for execution people freak when a lvl 1 got 10 in 0.