Email displaying in Registrant Management

I set the option for the email to not show in the Registrants Management, but it's still displaying it both in the front and backend. Actually, in the front end, if you select the show on Registrants Management, it displays the email twice.

Hi Lucy

Email (together with first_name) are the two required fields and it will always be displayed. You cannot hide it from registrants management or on registration form

Tuan