Remove All Invoice numbers

Hi,

Is it possible to remove all previously assigned invoice numbers when resetting the invoice starting number?

I want the invoice number to be generated when the order is marked as processing. This works correctly but its skipping numbers as they are already assigned to some completed orders. I previously had the invoice number generating on completed orders but due to the large amount of past completed orders my client has, it assigned invoice numbers to all these completed orders. Therefore new orders being marked as completed were skipping. I switched my settings to generate the invoice number when an order was marked as processing and it was working fine but unfortunately has now started the same behavior. I went back through my orders and found the numbers that had been skipped from orders dating a year back.

I removed the plugin and reinstalled it but the same invoice numbers are automatically assigned. Is there a way I can clear all the invoice numbers assigned to orders without having to go through them one by one? Unfortunately my client does not want to delete past orders so that is not an option.

Regards,

Conor