> You have to return the original registration document as well
I have never done that as usually the dog by then is in someone else's ownership, I think this might apply if the new owners want it to show on the registration cert for their dog that the endorsement has gone.
Certainly I have never returned a registration cert for any of mien.
It is rather annoying though that they confirm lifting of the endorsement to the person that put it on, but do not cc this info to the owner. so if your the owner ask the person that placed the endorsement to send you a copy of the letter confirming ti has been lifted, and if you placed the endorsement send the owner a copy to avoid any misunderstanding/worry.