How to make subtitles optional

[taggg]

I have two discs in which subtitles are always on and cannot be turned off. The discs can be cloned and the subtitles eliminated entirely -- but then they cannot be turned on, because they're gone.

Problem: how to make them optional using ffpegX - or some other application?

I suppose one way to get round this would be to extract the subtitles, then demux the dvd, then re-author the thing.

Is there an easier solution?

Thanks.

[Case]

1/ Are you sure the subs are not 'burned' into the video?
2/ myDVDEdit may have options to make the subs optional.
3/ MacTheRipper can override UOPs, including Subpicture stream change, if that is used to control your subs. Read the warning, though.