Don’t know about the game or if there’s any in-game option to clear saved data, but clearing your browser cache erases flash Shared Objects, which almost every game uses as a way of saving content. You would lose save data from other games as well though.
It looks like it’s a multiplayer game, so the data is stored on servers, not your local machine. Clearing any local data will not do anything good for you, the only way to start over would be if there’s an in-game option, or if you messaged the developer about it to see if they could reset your game profile.
