How can I request a refund with Google Play?
3. Tap Purchase history
You need to make sure that you have cancelled your subscription (see how: https://support.google.com/googleplay/answer/7018481), otherwise it won’t be possible to request a refund from Google. Once you have cancelled your subscription, click on "Request a refund" on the following link https://support.google.com/googleplay/answer/7205930