1) Firstly, create an Ap Invoice at Menu: 4 - 3 or from the Top Menu: Accounts payable - Invoice Posting.  Crediting that invoice or negating that amount above.

2) Then create a $0 cheque at Menu: 4 - 5 or from the Top Menu: Accounts payable - Cheque Posting, pick the above two invoices and they will cancel each other.