Open More → Settings and tap Delete my cloud data. Your save, scores, league history, friends, gifts and player name are deleted from our server straight away.
Write to liudasius@gmail.com with your player name and friend code (shown in More → Friends). We delete everything within 30 days.
Purchase records (order IDs) are kept as long as tax law requires, without your name. Uninstalling the game removes the data on your phone.