I don't know who the person is at Microsoft that decides people like things forced on them but that person needs to knock that crap off. Everything, not just Cortana, should have a way to be disabled without having to resort to registry edits. On a system running Windows 10 Pro or Enterprise edition, you can use Group Policy to apply this setting across multiple machines in an enterprise network; on a single PC, use the local Group Policy Editor, gpedit.msc, to open the policy Computer Configuration > Administrative Templates > Windows Components > Search > Allow Cortana and set it to disabled. On a system running Windows 10 Home, you need to make a manual edit to the registry. Find the key HKLM\Software\Policies\Microsoft\Windows\Windows Search (you might need to create this key if it doesn't exist), and then create the DWORD value AllowCortana and set it to 0.