Colour Cozy (by Digcy) has no accounts and keeps your progress only on your phone, so you are always in control.
Uninstalling the app also removes all of its data from your phone. Pictures you saved to your gallery stay there until you delete them.
Ad data is handled by Google AdMob. You can reset or delete your advertising ID in your phone's Settings, under Google, Ads. Google's controls: myadcenter.google.com.
Write to hello@digcy.com. We answer within 30 days.