By "ego" you mean ... self-identity ... self-image ... identity? One's "boundaries"?
BKs use the term but as with any BK use of language, they have given it their own mean which is flexible and malleable according to demand. In a simple way to mean "egotism", an inflated sense of self-worth. In a subtle way to mean any idea, opinion, stance, opposition to what group think or the opinion of the leaders. It is meant to be the first and most difficult of vices to overcome. Something entirely BAD.
To have any "self" is to not "have Baba". Of course, for the leaders, a load of people without any "selfs" are hell of a useful mental slaves to have around to tap for money and work for free!
Ego in the real world is used, based on Freudian Psychology (Das Ich), to mean the part of the mind that contains the consciousness. A set of psychological functions such as judgment, reality-testing, control, planning, defense, synthesis of information, intellectual functioning, and memory. In modern English, it could mean one’s self-esteem or, philosophically, one’s self.
I mention social and psychological boundaries because I think those are entirely trashed by 'surrendered' BKWSU lifestyle. You have no self mind ... you have no privacy ... no space. You are required to put aside your own morals and intuitions and just follow instructions. "Surrender everything", 100% of the self ... to what? A constantly changing set of demands being made on you.
So, to summarise my response, I am not quite sure what "ego" means in the BK world ... what was your experience before and is your experience now?