It’s possible two ways, one easy and one hard… To disable the splash screen when you open Rhino from a desktop shortcut, all you have to do is add /nosplash to the target in the shortcut properties:
"C:\Program Files\Rhinoceros 5.0 (64-bit)\System\Rhino.exe /nosplash"
(leave one space between)
That will not stop the splash screen from appearing when you open a file by double clicking on it, however. If you want to completely disable it, it’s only possible through a registry hack, see this thread (near the bottom).
–Mitch