complete del and destroy funciton for desgin

app/controllers/admin/designs_controller.rb

@@ -1,5 +1,7 @@
 class Admin::DesignsController < ApplicationController
   layout "admin"
+  before_filter :authenticate_user!
+  before_filter :is_admin?
 
 
   def index
@@ -26,6 +28,9 @@ class Admin::DesignsController < ApplicationController
   end
 
   def destroy
+    @design = Design.find(params[:id])
+    @design.destroy
+    redirect_to admin_designs_url
   end
 
   def create