If you right click on the Groove icon in Win 10, there's no uninstall option. But it is listed in the CCleaner 5.11 uninstall list, and the uninstall button "lights up" when you select Groove. Earlier today I used CCleaner to uninstall Camera and Voice Recorder, two other apps that are not supposed to be uninstallable, and both icons disappeared from the All apps list, and when I checked in Windows Store, both had install buttons, which worked when I tried them. I'm going to try uninstalling Groove and some other apps later, and see what a restart does. I'll post the results.