Writing off a receivable means nullifying the amount of the receivable from the general ledger by creating a correcting journal entry. The Write Off option in Connected Business is an actual write off routine. This will post a ledger transaction to the customer account per invoice or part of an invoice to be written off. This facility may be used for example, before sending a statement run.
So rather than sending statements (which would cost you) for outstanding balances less than $10, it would be better to write off these small amounts quickly and easily which is exactly what the routine was designed for.