Hide XFCE Panel with command line

 # Hide the XFCE panel:

xfconf-query -c xfce4-panel -p /panels/panel-0/autohide-behavior --type int --set 2
xfce4-panel -r

# Show the XFCE panel:

xfconf-query -c xfce4-panel -p /panels/panel-0/autohide-behavior --type int --set 0
xfce4-panel -r

0 = never

1 = Intelligently

2 = Always