Only a few steps are necessary to disable advertising. You can do this by signing up for an ad-free subscription, which is provided by the respective app store. Therefore, make sure that you are logged in to the store with the correct account.
Follow these steps to turn off the ads:
1. Open the Sudoku app
2. Tap on "Options"
3. Tap on the button next to “No ads”
4. Choose one of three options - 1, 3 or 12 months
5. Confirm your purchase for the App Store
If you still see ads, see "Why do I see ads even though I have a subscription?" for more information.