If you have decided not display ads to your app users then you can disable Contains Ads Label from Google Play Store.

1. Login to Google Play Console
2. Select the App, you want to disable ads on
3. Click Policy on the bottom left
4. Click App Content under Policy
5. Under Ads section
6. Click Manage
7. Select No, my app does not contain ads
8. Hit Save button on the right bottom.

That’s all.!!