Xfce4: Show / Hide sleep / hybrid sleep / suspend button

You can create the following property controls xfconf configuration items:

xfconf-query -c xfce4-session -np '/shutdown/ShowHibernate' -t 'bool' -s 'false'
xfconf-query -c xfce4-session -np '/shutdown/ShowHybridSleep' -t 'bool' -s 'false'
xfconf-query -c xfce4-session -np '/shutdown/ShowSuspend' -t 'bool' -s 'true'

http://linux.chrissweeney.co.uk/topic.php?t=53