>I haven't tried Method 3 in the link above so I'm not sure if even that stops loading of the Cortana service entirely.
>
>There's a comprehensive discussion of this at https://superuser.com/questions/949569/can-i-completely-disable-cortana-on-windows-10 . Looking at my system I see I applied the Group Policy setting as well (I'd forgotten I did that). Despite all that, Cortana still loads on my system but apparently with minimal resource usage (see image).
>
>It looks like one of those "Windows components" which are deeply hooked into Windows and difficult or impossible to remove entirely.

I have found a way.

This comes from the link you provided. Down below, there is a mention about trying to rename the Cortana directory. However, in order to do that, it must not be running. The problem is Cortana is reloading itself. Thus, go on that directory, rename and a message will say this is not possible with a Retry possibility. While at it, simply move the window to the left. On that Task Manager window, move it a little bit to the right. Now, we have about 1.5 seconds of a window of opportunity to be able to rename it. Click End Task, and rename right before it has a chance to reload back. That works.