Delete an individual registration, which includes Application ID, Device Type, and User Name. This is useful for deleting orphaned registrations, which can occur when a user is no longer using an application on a device, or has obtained a new mobile device, which requires its own registration. It can also be useful for clearing a registration while troubleshooting configuration issues. Once the registration is deleted, the user will not be able to use the application on the device unless they reregister the application.