I don't think you're missing anything. The function doesn't exist in Payables. Deleting a vendor is only permitted when there are no transactions, history or 1099/retainage/PO activity. You can delete a vendor with history, it you've set this option in the company profile. Using a utility that worked with ACCPAC sounds risky, but possible. Alternatively, you could create a filter to restrict the list to those you'd like to delete. You'd still have to manually delete each one.
Perhaps another function for the
Toolkit for Adagio.