Trying to cancel my auto loan after a year

I made a horrible and stupid mistake of going alone to a dealership to purchase a car, I have an interest rate of 20.49% and will have paid 25k by the time I am finished with all of my payments. It's not that I can't make the payments but I realize how much more I will be paying than the car is actually worth (2008 Buick Lacrosse). At this point is there anything I can do to cancel the loan and return the vehicle without them trying to get me to pay the rest of it off?