You can find your Apple subscription management inside your account settings for your Apple ID, which can be accessed for example via the App Store. There you can can cancel any subscription and trial subscriptions.
- Open the App Store on your iPhone or iPad and tap on your user icon (upper right).
- In your account management tap again on your user name/icon.
- Scroll down the page to find the entry 'Subscriptions' and tap on it.
- The next window displays all running and canceled subscriptions made by you.
- Tap on the CyberGhost entry to open the details page.
- Cancel your subscription.
If you want to have a payment examined, please visit reportaproblem.apple.com and explain, why you want a refund. It's usually a fast procedure.