Windows 10 - Disable warning notification about disabled firewall via GPO
It's not possible to disable the firewall notifications alone, but since Windows 10 build 1607 it has been possible to disable all Security and Maintenance Notifications using
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Notifications\Settings\Windows.SystemToast.SecurityAndMaintenance\Enabled = 0 (DWORD)
UPDATE: According to Ladislav Louka, the required value has changed to 1 since build 1809.
Either add this registry key directly via Group Policy or create a custom ADMX template for it. See Disabling Windows 10 Notifications via Group Policy by Jeffrey Harness.
I think any of these notifications equally doesn't need attention of a single user, but these settings must be monitored & maintained by the administrators, instead. The scope of this modification seems ok.
Click the Start button, type Security & Maintenance and then click on the Security & Maintenance control panel option. You can also go directly to the control panel and get there that way.
Choose Change Security and Maintenance settings.
Uncheck Network Firewall
Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender Security Center -> Notifications -> Hide all notifications