app/views/admin/users/_edit_form.html.erb
<%= simple_form_for(@admin, url: admin_user_path) do |f| %>
<%= f.error_notification %>
<div class="form-inputs">
<%= f.input :username %>
<%= f.input :password %>
<%= f.input :password_confirmation %>
<%= f.input :superuser %>
</div>
<div class="form-actions">
<%= f.button :submit, "Edit Admin", class: "btn btn-primary" %>
</div>
<% end %>