Hi,
Thank you for writing to Microsoft Community Forums.
Seems that you want an option to stop/revoke the option for manual Certificate request and export Private Key.
However, for concern/queries related to Certificate, let me help to point you in the right direction. I would suggest you to post your query in Q&A Forum where you will find professionals with expertise on certificate revoke policy and that would be the appropriate forum.
Regards,
Aditya Roy
Microsoft Community – Moderator