suppose a child were raised by a human parent and at some point becomes a teenager and thinks, this person isn't worth listening to at all?

If that's possible then I guess it's possible to tell the AI raised teen the AI isn't really a person, you just need to find the right moment to give them that thought.

Basically you need another AI monitoring development to pick the optimal time to inform the child that the first AI is just a computer program.

OR you could do it like the movie I Am Mother https://www.rottentomatoes.com/m/i_am_mother