Typing
> New-NetFirewallRule -DisplayName "Search" -Direction Outbound -Action Block -Profile "Domain, Private, Public" -Program "C:\Windows\SystemApps\Microsoft.Windows.Cortana_cw5n1h2txyewy\SearchUI.exe"
in elevated Powershell should work.
Typing
> New-NetFirewallRule -DisplayName "Search" -Direction Outbound -Action Block -Profile "Domain, Private, Public" -Program "C:\Windows\SystemApps\Microsoft.Windows.Cortana_cw5n1h2txyewy\SearchUI.exe"
in elevated Powershell should work.