Unsubscribe from Google Drive storage plan

View, change, or cancel your subscriptions - https://support.apple.com/HT202039 - "Learn how to view your subscriptions that renew automatically, change your subscription period, and turn off Automatic Renewal." "If you don’t cancel more than 24 hours before your renewal date, your subscription might renew." Deleting an app does not cancel a subscription. Stopping the auto-renewal of a subscription only does that, it does not immediately stop the subscription (with the exception of free trials), nor result in any refund.

If you do not see it there then:

Get help with subscriptions not billed through Apple - https://support.apple.com/HT207865