Yes, here's the link from which I found the fix.
Completely Disable Cortana in Windows 10 via Registry or Group Policy
Scroll down to the center
Disable Cortana using Registry
If your Windows does not ship with Group Policy, type regedit in the taskbar search and hit Enter to open the Registry Editor.Navigate to the following key: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Windows Search
Now in the left pane, right-click on Windows Search key and select New > DWORD (32-it) Value. You will it formed in the left pane. Give this newly created DWORD value a name AllowCortana and set its value to 0 to disable the feature.
To enable Cortana again, you may delete this AllowCortana value or change it from 0 to 1.UPDATE: Andrew Rodecki from Elkhart contacted me and mentioned that the path for creating the AllowCortana DWORD. It is now: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Search
This is where Windows 10 1903 is cheeky. Microsoft are lying that Cortana is separable. I don't define that as separate when Cortana still uses network data.
So in 1903 basically Microsoft have removed Cortana Search from the App history preventing you from knowing that it is chewing network data. Fortunately for us we can still find out by going to the Task Manager Processes Tab.
Scroll down to Cortana where it shows Suspended. Start clicking start menu button while the Task Manager is being displayed and see for yourself. The network to the right in your Task Manager Processes tab will show Cortana is using network!
Microsoft think they are clever to fool us. Once you make those registry changes and add AllowCortana in those following regedit lines you should see the network usage from now on remain to 0 Mbps regardless of how much you click the start button!
I hope this helps. This is also my future personal reference in case I need to reinstall Windows 10 again I can look back at the solutions to redo this again. Absolutely Pathetic from Microsoft to treat us like that! We shouldn't have to do all these modifications ourselves every time on a fresh install.