you chop off their head, which contains their brain, you chop off their head, the tail will regrow a new head, and that new worm will remember the original training.

you can chop them this way. However you cut, the record is something like 275 pieces, if you chop them into pieces, every single piece regenerates to make a perfect little worm. So every piece knows exactly what the whole thing is supposed to look like, and they rebuild.