Prasad,
We are getting a little distance away from your original topic.
I will take your last question to mean you wish to ALSO turn off ATP checking for deliveries. You can do this at the requirements class level (OVZG) or the item category level (0VLP).
I don't know your detailed business requirements. I hope you are including your SD colleagues in all of your decisions, since these decisions will probably impact them.
Best Regards,
DB49