Hi, I wouldn't of created the sales invoice.  I would of done a journal entry to the revenue account and the shareholder's loan account.  

If you're trying to get it out of the Accounts Receivable system, the easiest way is probably two steps:

1.  Record a 'receipt' showing it as paid.  This will debit a bank account or deposit clearing (incorrectly), and credit accounts receivable (correctly).

2. Do a general journal entry to debit the shareholder loan account and credit the bank account or deposit clearing account (fixing the phantom receipt).

Then, when the shareholder gets around to paying for the item, it will just be a general journal entry to debit bank/credit shareholder loan.