hi, m8
you don't need demux the vobs to remove audio (and subtitles) streams ... just use ifoedit (get it on doom9.com) to create new vobs ... If necessary (if you have only a .vob file - without .ifo file), you can create a .ifo file ...
btw, to demux vobs, i mean you can use vobedit (get it on doom9.com too)
cU