If I feel that my child is old enough to have full control over their HMD Fuse phone, how do I remove it completely from the HarmBlock+ sevice?

You can perform “Remove device without factory reset” from the Kid’s device settings in the guardian HarmBlock+ app. This will remove all the parental control from the kid’s device and keeps all the user data so the child can continue using it. You may then contact the retailer from which you purchased the device. The retailer will then pass the request on to us at HMD to stop the service.