If you purchased Nest Aware directly from Google Nest, you can cancel your subscription in the Google Store.
If you purchased through one of Google's partners, contact the partner to cancel your subscription. For more information, including how to tell if you purchased your subscription from a partner, visit our FAQs about purchasing Nest Aware through one of our partners.
Check the "Cancel through Google Store" steps here:
Manage your Nest Aware subscription on the Google Store - Google Store Help
If it turns out you originally purchased Nest Aware from a partner, the subscription will say Nest Aware with the details of your plan. Below this you’ll see Subscription managed by (partner name). There will also be an alphanumeric subscription ID. You'll need to contact the partner it shows, give them this subscription ID and they can help you cancel it.
Thanks for posting here in the Community forum, and I'm sorry to hear about the situation. I want to check if you managed to follow the steps from the link that davidking has provided. Please let us know if you still have questions or concerns, as we'll be willing to assist you further.