You can cancel your subscription in the subscription settings of your Apple ID through the settings of your device. Please complete this 24 hours before the end of the subscription period to avoid being charged.

You can cancel your subscription in the following way:

1. Open the Settings app.
2. Tap your name.
3. Tap Subscriptions.
4. Tap the subscription for Magic Puzzles and tap Cancel.

For additional information, please follow the link: https://support.apple.com/en-us/HT202039