Starting with version 1.2.0, you can reset your game progress in Beach Buggy Racing 2.
Go to "Profile/Settings" by clicking the button in the upper left hand corner of the main screen. Click the "Manage Account" button. From there you can "Reset Game".
WARNING! Resetting your game completely erases everything in your game, including any in-app purchases you may have made. Once it's erased, there is no way to get it back again.