Fonts and Fonts Disabled folders in OS X Mountain Lion
If you're currently having no problems without those fonts, actually deleting them should not cause any problems. The system just ignores the fonts in the folder "Fonts Disabled" so there should be no effect on the system. 

Just be careful you don't delete the following fonts:


Keyboard
Geneva
LastResort
Monaco
LucidaGrande
Helvetica


located in /System/Library/Fonts. These fonts are used by the system. 
See also http://www.macworld.com/article/1051630/tcofonts.html