spree_paypal_express/app/views/admin/payments/source_forms/_paypalexpress.html.erb

<% content_for :head do %>
  <script type="text/javascript">
    jQuery(document).ready(function(){
      $("label:contains('<%= payment_method.name %>')").hide();
      $("label:contains('<%= payment_method.name %>') input").disable();
    });
  </script>
<% end %>