logon to the Xen system
$ xl help // list help; it's not xl --help
$ xl list // show VMs running
$ xl shutdown // graceful shutdown
$ xl destroy // forceful Power off
$ xl reboot
$ xl info // current xen information
$ xl console // attach to domain's console
$ xl vncviewer // attach to domain's VNC server
$ xl rename // rename domain
$ xl top // monitor vm
you had better use XCP-ng Center application.
xl help will give help to use xl commands