It depends on what you are using for software base. If you have eliminated *ALL* of your OS 9 materials, and you are certain that you will not need them tomorrow, then you may remove those 9.2.2 materials. I would keep the System Folder intact, however, to minimize restoration time.
Remember that an OS 9 System folder holds all the cards in the deck... you can migrate it off to a CD-ROM and bring it back if you needed to.
If you really have a space crunch problem, perhaps it is time for a new larger drive, or to migrate some of those things that you don't use and won't use anymore. Static files, such as music, may be migrated off to CD/DVD Roms if you need the space.
Just be sure to make backups of whatever you remove. You never know when you will need them again.