Facebook Page admins are publicly displayed only if admins have chosen to feature their profiles.
However, there are some situations where you might want to contact a Facebook page admin or want to find out who is the owner of a Facebook page.
Egyptian security researcher Mohamed A. Baset has discovered a severe information disclosure vulnerability in Facebook that could have allowed anyone to expose Facebook page administrator profiles, which is otherwise not supposed to be public information.
Baset claimed to have discovered the vulnerability in less than 3 minutes without any kind of testing or proof of concepts, or any other type of time-consuming processes.
read more source :
https://thehackernews.com/2018/02/find-facebook-page-admin.html