I need to void an invoice. Is there a way to also delink the associated sales order while voiding it?

Yes, you can delink the associated sales order while voiding an invoice. To do this:

1. Go to the Sales module and choose Invoices.
2. Select the invoice that needs to be voided and click More.
3. Choose Void.
4. On the following page, enter the reason for voiding and enable the option Dissociate invoice from sales order.
5. Click Void it.