If you connected your game to Google Play Account / Game Center / Facebook it cannot be reset on that account as far as I know. You will need to create a new account.
If it isn't connected to a cloud saving service, you can Clear App Data and it will let you start from scratch.
I do not believe just "unlinking" the app from your Google Play Account for example, will work. It doesn't for similar games.
If you use Android it's very easy to create multiple gmails. All my devices have several accounts attached. Sometimes I need to remove the others before I open a game for the first time because it autoselects, othertimes it prompts a window to select which account to use when you launch.
You can also demolish everything and start over.
