Should not create Invoice for delivery

Hi,

We created Order-->Delivery

Order type is assigned with delivery related invoice type.

Sales made against only one customer (Our customer is one time customer)

There are nearly 1500 deliveries.

Now client says they will pass single finance entry,they dont want to created invoice with reference to each delivery.

So we decided to remove the billing type in VOV8,but still we can create invoice.

Then removed the copy control between delivery type and invoice type,then we can restrict creation of invoice.

Apart from this ,is there any way.

Thanks,

Pradeep M