Color Cluster does not require account creation for its core gameplay loop. Best scores, settings, and related progress are stored locally on your device.
If you want to remove local Color Cluster data, delete the app from your iPhone or iPad. If you used optional Game Center features, leaderboard records are managed through your Apple account and Apple services.
For privacy questions or help understanding what data may remain in Apple services, contact support@hiddinkdevelopment.com.