Skip Authenticate method in Rails

I have a Sessions controller that requires authentication for creating a session using .authenticate method of has_secure_password defined in the User model, as per below:

Edit:

class User < ApplicationRecord

 before_save { self.email = email.downcase }



# Relationships

 has_secure_password

 has_many :pedidos



 # Validations

 VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-.]+\.[a-z]+\z/i

 validates :nome, presence: true

 validates :empresa, presence: true

 validates :email, presence: true, length: { maximum: 255 },    

                format: { with: VALID_EMAIL_REGEX }

 validates :cpf, presence: true, length: { minimum: 11, maximum: 14 }

 validates :password, presence: true, length: { minimum: 6 }    



 def admin?

    self.admin

 end

end

SessionsController

def create

    user = User.find_by(email: params[:sessions][:email])

    if user && user.authenticate(params[:sessions][:password])

        flash[:success] = "Seja bem vindo(a), #{user.nome}!"            

        session[:user_id] = user.id

        redirect_to user

    else

        flash.now[:danger] = 'Não foi possível realizar o login, '

        flash.now[:danger] += 'combinação usuário/senha inválido'

        render 'new'

    end

end

Now I created an admin/Users controller that I would like to perform database operations without having to enter password and password_confirmation fields. In the current scenario I'm getting error messages saying "password and password_confirmation can't be blank"

How should I proceed? Thank you.