How do I get rid of a face defined with defface?

[Alan Mackenzie]

Hello, Emacs.

In CC Mode, some debug faces are generated with, e.g., 

    (defface c-debug-is-sws-face ....)

.  Certain macros generate additional code when, e.g.,

    (facep 'c-debuf-is-sws-face)

holds.

I now want to turn off these debugging facilities, and to get these
macros to generate just the normal code, I need to get rid of the face
c-debug-is-sws-face.  I can't find any mention in the manual of how to
do this (this may be a manual bug), nor any statement that it is not
possible (again, a possible manual bug).

So, can I get rid of this face?  If so, how?  Whether or not, where is
the spot in the manual saying so?

Thanks in advance for the help!

-- 
Alan Mackenzie (Nuremberg, Germany).