Disabling won't help when it's so bad the Finder won't even let you touch it. That alone may make it difficult to remove. Some things to try:
1) If you have OS X installed on another drive (I always have an external with OS X on it for emergency booting), start up to that drive. Your main drive will then be just another data drive. The font will not be active and you may then be able to remove it.
2) Copy any good font to the desktop. Give it the exact same name as the bad font. Then drag and drop the good (but deliberately misnamed) font into the folder containing the bad one. Tell it to replace the existing file.
3) If you can't do number 2 because the system tells you it's in use, boot into Safe Mode (restart and hold down the Shift key). When you do that, only certain fonts are allowed to load, which means the bad font will not be active. Try replacing it again with an identically name file, or see if you can just delete from the Finder window.
4) While still in Safe Mode, launch Terminal. Enter the following line, or copy/paste it from here:
sudo rm -R
Don't hit enter yet. Put a space after the -R, then drag and drop the bad font into the Terminal window. It will add the path and name of the font to the command. Now press Enter and enter your admin password (it will ask). The font should be removed.
