obsolete 4alpha-carboxy-4beta-methyl-5alpha-cholesta-8-en-3beta-ol:NAD(P)+ 3-oxidoreductase (decarboxylating) activity (obsolete GO:0103066)
OBSOLETE. Catalysis of the reaction: 4alpha-carboxy-4beta-methyl-5alpha-cholesta-8-en-3beta-ol + NAD(P) = 4alpha-methyl-5alpha-cholesta-8-en-3-one + carbon dioxide + NAD(P)H.