added delete all variants button

app/controllers/admin/variants_controller_decorator.rb

@@ -5,4 +5,11 @@ def regenerate
     product.do_create_variants(:recreate)
     redirect_to :action => :index, :product_id => params[:product_id]
   end
+
+  def delete_all
+    product = Product.find_by_permalink(params[:product_id])
+    product.variants.delete_all
+    redirect_to :action => :index, :product_id => params[:product_id]
+  end
+
 end

app/controllers/orders_controller_decorator.rb

@@ -29,7 +29,7 @@ def enhanced_option_create_before
     end if params[:option_values]
 
     if quantity > 0 && variant
-      if quantity > variant.on_hand
+      if Spree::Config[:track_inventory_levels] && quantity > variant.on_hand
         flash[:error] = t(:stock_to_small) % [variant.on_hand]
       else
         @order.add_variant(variant, quantity)

app/views/admin/variants/index.html.erb

@@ -5,6 +5,13 @@
   :confirm => t(:regenerate_confirm),
   :style => "float: right"
 %>
+<%= button_link_to t(:delete_all),
+  {:action => :delete_all, :product_id => params[:product_id]},
+  :method => :post,
+  :icon => 'exclamation',
+  :confirm => t(:delete_confirm),
+  :style => "float: right"
+%>
 
 <%= render :partial => 'admin/shared/product_sub_menu' %>
 

config/locales/en.yml

@@ -7,4 +7,6 @@ en:
   variant_price: Variant price
   regenerate: "regenerate variants"
   regenerate_confirm: "This will wipe out all your current variants\nAre you sure?"
+  delete_all: "Delete All"
+  delete_confirm: "Are you really sure you want to delete all current variants?"