so far none of my friend do it officially, they just don't show up to live in canada anymore.. and no renewal of the maple leaf card after expiration. and when they came again, they came as visitor...
guess if they want to do it officially, they will have to write to candian high commissioner, saying they deny to be landed immigrant, and return, the health card, driver's licence (if any) and the maple leaf card.. stating when they will be leaving canada and stop enjoying the benefit..