Admin user did not search in Security console

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Dear ,

I have all users list which i extracted in PER_USERS table. But i am little confused that in our oracle fusion some users created by admin. so when i search admin in security it did not find or search. so how can i check admin users or any guidance about it.

Because we pay service / support charges for 3rd party and now we are planning to handle or support oracle fusion ourselves. so we want to know about admin user and why it is not search 

Thanks