Click on the Apple icon and select
Keyboard system preference icon.
Customize Touch Bar... button.
Move your mouse down, off your screen and INTO the touch bar. This will highlight each menu item. Highlight the Siri button, click, and drag the Siri button upward and out of the Touch Bar. It will now disappear.
You can optionally add a new button to replace the Siri button, but I chose to leave it empty because I inadvertently click in the space all the time.
You go to hell Siri and you die there. Now that you've disabled Siri, perhaps you'd like to disable the MacBook Pro Touch Bar and revert it to its former Control Strip glory!