For parents who may be concerned about accidental purchases from their child or have had a case of accidental purchases in the past, please refer to the options available to you for preventing further accidental purchases.
If you are using an Apple iOS device, please refer to https://support.apple.com/en-us/HT204396
If you are using a Google Android devices on Google Play, please refer to https://support.google.com/googleplay/answer/1626831
For other app stores, please refer to them respectively.