If you wish to disable automatic renewal of a service subscription for in-app purchases you will need to manage your Subscriptions. Please click here for Apple’s support document on how to manage subscriptions.
One reason to disable automatic renewal is for original Roomie Remote customers that have the Roomie Service, but wish to take advantage of the new Simple Service to use the new version 5. To upgrade from the Roomie Service, disable your Automatic Renewal for the Roomie Service and then purchase the Simple Service. The Simple Service is provided as an in-app purchase.