Dinner sounds wonderful!
Normally, you can identify the SID/STAR by its name or name transition combo... at LAX you might approach using the HEC.DOWNE4 transition and STAR and depart via the LAX6.TRM departure. A route from LAX to SAN might look like KLAX LAXX6.TRM TNP.BARET4 KSAN in FSBuild and the SID and STAR are easy to identify - to remove them you just edit the route string to remove the SID and STAR and press 'BUILD' and get (in this very brief case) KLAX KSAN. Obviously, any significant route will contain waypoints between the SID and STAR but the principle is the same. FSBuild does include an option in the 'Build Options' menu item to exclude SIDs/STARs. Other planners might use a different notation and you might need to look at terminal charts to figure out what's what.
DJ