obsolete 4alpha-carboxy-5alpha-cholesta-8-en-3beta-ol:NAD(P)+ 3-dehydrogenase (decarboxylating) activity (obsolete GO:0103067)
OBSOLETE. Catalysis of the reaction: 4alpha-carboxy-5alpha-cholesta-8-en-3beta-ol + NAD(P) = 5alpha-cholesta-8-en-3-one + carbon dioxide + NAD(P)H.