TOPIC: project future value changed after the team start development.

one of the exam questions is about a future that you get to know as a team and scrum master from customers that the value of one feature is no longer important to customers. but the team started to work on this feature and developed about 20 %.
in the exam answers nothing about project owner to give feedback what to do. as project practitioner what should you do?

In my view as feature is no longer valid for customer and have no value for business, so as a project manager in my view ,should have put the feature against change control board to reject