Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
On the link below are the steps to check your eligibility for a refund and to cancel the Microsoft 365 basic subscription, and while managing your account, you should also remove the recurring billing on the subscription you do not need.
Regarding a refund, you may be able to get a refund for the latest payment, but you would not get a refund for the last two years that the two subscriptions have overlapped.