Hi Anne,
I'm guessing and thinking out loud here (well, "onscreen")...
You might have to start up from another disk and then drag OS9 to the trash. HOWEVER! I don't know if that will mess up your OSX because it will be looking for an OS9 system folder. Better get real advice from a real wizard on this before proceeding.
For this reply not to be a total waste, though, the following might help with your space problem:
http://monolingual.sourceforge.net/It's a little program called "Monolingual" that takes out extra code for languages that you are never going to use on your Mac. It can save many, many megabytes.
Another space saver is to remove printer drivers that you aren't going to use. If you only use a Canon, then you don't need Epson, HP, etc. They can be space hogs too.
Good luck!
-Brian