hai I want to disable the post email Notifications for all users
Your title and body have conflicting statements - are you looking to disable all emails, or only emails for posts?
only emails for posts
If (big if), you are talking about digests, there is a site setting for that:
disable digest emails
And if you are talking about emails you get when someone replies to your post - you could run change the default setting via site settings, and existing user settings from the ruby console, but I don’t think you can completely disable it without affecting other emails.