app/views/users/edit.html.erb
<%= render 'header', :title => 'Update user' %>
<section class="main-content">
<%= render "flashes" -%>
<%= simple_form_for @user do |form| %>
<%= form.input :email, disabled: true %>
<%= form.input :admin %>
<%= form.button :submit %>
<% end %>
</section>