Newsletter opt out

gistfile1.erb

Controller Action

  def newsletter_opt_out
    @newsletter = Newsletter.find_by_email(:email)
      @newsletter.destroy
      respond_to do |format|
        format.html {redirect_to :back, notice: t('newsletter_opt_out')}
      end
  end
  
  Route
    delete 'newsletter_opt_out' => 'pages#newsletter_opt_out', as: 'newsletter_opt_out'
    
    
  
  View
  <%= form_for :newsletter, url: {action: "newsletter_opt_out"}, :html => { :method => :delete } do |f| -%>
  <div class="form-group">
    <%= f.text_field :email, :class => 'form-control' %>
    <div class="controls">
      <%= f.submit "Opt out", :class => 'btn btn-primary' %>
    </div>
  </div>
<% end %>


Error: undefined method `destroy' for nil:NilClass

Newsletter.find_by_email(params[:email])