I have no idea why Microsoft has removed the ability to uninstall stock apps from Windows 10. As a consumer, it just makes no sense to me why I have to have a bunch of unused apps on my system if I don't want them. Hopefully this change isn't permanent.
Microsoft introduced the ability to remove unwanted stock apps in build 14936 for Windows Insiders, but now it’s taken back that option. While you’ve been able to uninstall certain Windows 10 apps since launch, as of October, Insiders have been able to delete apps such as Calculator, Groove Music, Mail and calendar, Movies & TV, OneNote, and Xbox, but that’s no longer the case.
