Thanks a lot !
But this website of government of Canada says it is not possible to relinquish your PR status
Here is the that page
http://www.canadainternational.gc.ca/india-inde/visas/pr_return-retour_rp.aspx?lang=eng#Travel_
One more question if you want to get sponsered again to Canada in a short time (like a year after as a dependant child in my case) , does relinquishing your PR status affects the application in any way ?
Thanks !