If you would like to start from scratch, you'll need to create a new game account.
To do that:
- Uninstall Little Big Robots;
- Log in to Google Play Games with a Google account that doesn’t already store any Little Big Robots progress: Google Play Games → Settings → Tap your current Google account → Add another account (or select one that doesn't already have LBR connected);
- Install Little Big Robots;
- Launch the game;
- In order not to lose access to your new game account, connect it to a new Google Play Games account: In-game Settings Menu → Google Play Games ‘Connect’ button.
⚠ NOTE: Unfortunately, it’s not possible to start over using the same Google Play Games account