Find the OS 9 system folder and drag it to the trash. Make sure that the one you trash is not the OS X one. The OS X system folder is called System while the OS 9 one is called System Folder. It may, or may not, have a happy Mac face on it.
Take the Applications (OS 9) folder and drag it to the trash. You may find other applications laying around, the OS 9 documents folder may also be trashed.
Empty the trash and you are about done.
P
I have a Powerbook G4 400Mhz. It has MacOS 9.1 and 10.3.9 on it. I have upgraded all my older programs, and don't need MacOS 9.1 or the programs that run under that operating system. Is there a way to eliminate only MacOS 9.1 and all of the programs that run under it without having to erase the entire hard drive and re-install MacOS 10.3.9?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic