Only a few steps are necessary to deactivate the ads. This is done by signing up for an ad-free subscription, which is provided by the respective app store. Therefore, make sure you are logged in to the store with the correct account.
Follow these steps to disable ads:
1. Open the Crazy Eights app
2. Tap on the shopping cart icon in the top right corner (Shop)
3. Select the "Ad-free" tab
4. Choose between the three options - 1, 3 or 12 months - and confirm with "Okay"
5. Confirm your purchase again for the App Store
If the ads do not disappear right away, restart the app and/or follow the steps above until point 4 and tap on "Restore" in the "Ads" menu. This will renew the connection between the store and the app.
If you still get ads, see "Why do I see ads even though I have a subscription?" for more information.