If your not in a hurry, the sun will do most of the work for you. I put
Cetol on my teak a few year ago and didn't like it (what was I
thinking). After two years in the sun most of it was gone and the rest
came off very easy with a finish sander and 120 grit. Didn't remove
much teak. If I were to do a deck I would use a floor scrubber with the
finnish sanding disks the floor guys us for oak flooring.

Regards, Ron