Chop it off, let it callous, and pot it up where the aerial roots are. It might be better to wait until spring for the best time to do this, but now is all right, too.

cactusmcharris, above, is correct. I have a couple of Sans similar to your photo that produce offsets and pups in this way. One was listed as a Lavranos of some type, and the other is a Ballyi of some time. Both are pretty prolific. Interesting to watch, but sometimes annoying to manage. Depending on where you are, his advice about waiting until spring is also correct. (I'm in Florida, and we can pretty much propagate any time. In fact, my Sans grow far better in "winter" than in the dead heat of Florida summers.) . When you cut, make sure to get an aerial root because that will be the point from which the main growth takes. Mine grew roots very slowly at first, but then after about 6-7 months in new mix, they picked up speed!

Good advise but watch watering for maybe a month due to new section rotting. They can go a lone time with out water.