How to cancel Azure subscription without administrator authentication

Question

My organization is a subscriber to Azure (the account owner email is <Mod remove PII>@musicchildren.org.hk). The person (Raymond), who was the administration, has recently left our organization. Although he left the Azure portal login in email (******@musicchildren.org.hk) and password, the login needs authentication which our organization does not maintain the authenticator app. We are unable to sign in Azure portal. We can't read the invoices nor manage anything about our Azure subscription neither.

Since we have subscribed other Azure service through other agent, we decided to cancel our existing Azure subscription. We are not stuck and can't proceed. Could you please lead us the possible way to successfully cancel our Azure subscription as soon as possible. Since we are a NGO, we can't afford to continue subscribing.