[gowld]

On my machine right now, Cortana is Disabled in settings and Group Policy settings (you can't disable all of Cortana from regular settings, only the "Hey Cortana" and various ad popups) but the UI is clearly still visible in my taskbar.

[NiveaGeForce]

If you select disable or disable its permissions in settings, it's disabled.

The fact that there is a Search UI on your taskbar (which you can remove with right click), doesn't imply that Cortana's data collection is enabled.