What they have done in version 1803 is change the way cortana is activated. If you are running version 1803
you will have to run this reg file to accomplish the same thing.
You will still half to go to settings and turn off getting to know you.Turn off cortans from searching the web .reg file.
This applies to the Windows 10 version 1703 Creators Update.
First go to
1. Settings
2. Privacy
3. Speech, inking, & typing
4. Turn off Getting to know you. (Everything you type in or say to Cortana is kept on the cloud for Microsoft to see what you are doing.)After you have done that run the .reg file and reboot. You can than use it to only search on your hard drive.
What I do is right click on the task bar, select Search and click on Hidden. If you want to use Cortana to search on your hard drive than just click on the start button in the lower left and start typing. Cortana will come up with your search results.