Devise for login

Installed the gem called 'Devise' with 'Simple Form' that generates a User model with additional fields of first_name, last_name, and phone_number. In addition, added presence validations for first_name, last_name, phone_number with a regex format for phone_number. Addtionally, added additional text boxes to their views that allows users to sign up and edit their information.
Is there a way to separate this out into an .erb template somewhere? I'd love to avoid HTML in `.rb` files if we can.