You can hide your taskbar using Windows 11 settings, but that won't hide it completely. The only way to do that is to use a third-party application.

The latest Windows 11 preview build finally enables the ability to view the notification center and calendar flyout from the Taskbar on secondary monitors.

Microsoft has fixed a known issue causing restart loops and taskbar problems on Windows 11 systems after installing the June KB5039302 preview update.