GPO to always hide system tray icons in Windows 10

Solution 1:

You need to enable the "Hide the Notification Area" setting under:

User Configuration\Administrative Templates\Start Menu and Taskbar\Hide the Notification Area

From the GP Management console explanation for the setting:

This setting affects the notification area (previously called the "system tray") on the taskbar.

Description: The notification area is located at the far right end of the task bar and includes the icons for current notifications and the system clock.

If this setting is enabled, the user’s entire notification area, including the notification icons, is hidden. The taskbar displays only the Start button, taskbar buttons, custom toolbars (if any), and the system clock.

If this setting is disabled or is not configured, the notification area is shown in the user's taskbar.

Note: Enabling this setting overrides the "Turn off notification area cleanup" setting, because if the notification area is hidden, there is no need to clean up the icons.