How do I request refund from Apple?

All you can do is try:

Request a refund for apps or content that you bought from Apple - Apple Support

In most cases all transactions in the App Store are final, but at times Apple may provide a compassionate refund. It should never be expected though. Some apps offer Free Trials to see if you like the service they offer, while others do not. You cannot make every app a free trial by trying it out and requesting a refund later. If trying it out first is important to you, then only choose the ones that offer a free trial and to avoid any charges, you have to cancel at least 24 hours before the trial period ends.