You can use Font Book to control which fonts are available to Mac OS X applications. Fonts installed in the Mac OS 9 System Folder can be disabled using Font Book's Disable feature. A "disabled" font becomes unavailable to Mac OS X applications, but continues to be available to Classic applications. Disabling a font in Font Book is different than removing it.
To make a font unavailable to Classic applications, remove it from the Mac OS 9 System Folder. For help doing this, see technical document 106737, "
Mac OS X: How to Add or Remove Classic Fonts."