Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
iOS version is free.
If you don't want the paid version, cancel as soon as possible.
If you signed up directly with Microsoft, Please go to https://account.live.com
Sign into your Microsoft account. Then go to Services. Click on Manage for the subscription plan you want to cancel.
If you signed up with Apple App Store, you cancel it via Apple's subscription management in your Apple account.