% cd [AllegroGraphInstallation]
% .\AllegroGraphServer.exe --service-stop
The Services control panel applet can also be used to start/stop/restart the service.
To stop an AllegroGraphServer that was started in console mode (not as a service), simply close its console window.
$ kill -TERM pid
and on Linux:
$ /etc/rc.d/init.d/agraph stop
will stop the service.