It depends on the contract the carrier has with the phone manufacturer. Typically, it should be removed when you access it through the Settings > Applications > All > Boost Icon Pack. When you tap the app, the Force Stop and Uninstall button should be available. If the Uninstall is missing, then the app is bundled with your phone and the only way to remove it is through the root process. This involves gaining access to the root file system from where you can remove system apps easily, but it might break the warranty.
