Deleting a sales invoice is depending on the status of the invoice.
1) DRAFT INVOICE
Go to Invoice Option > Delete
2) AWAITING PAYMENT INVOICE
- Go to Invoice Option > Revert
- The invoice status will turn into Draft status
- Select the draft Invoice and delete at Invoice Option
3) PAID INVOICE
- You need to delete the payment transaction associated to this invoice by clicking View Receipt.
- Go to Receipt Option > Delete Transaction
- A confirmation pop up will appear. Click OK.
- Go to Invoice Option > Revert. This will change this invoice status to Draft.
- Select the draft invoice and delete at Invoice Option.
Delete vs Void
Either you delete or you void the invoice, the invoice number is spent and you cannot recycle the number again. Delete will remove the transaction completely. Void action will only cancel the invoice without deleting it.