The management of your payable accounts must be done from the [Finance > Payable Accounts] menu.
This payable accounts panel will be fed by the transactions you post manually, the recurring transactions and future refunds posted in the bookings page and the ideal is that on your daily financial routine, it stays with no pending payable accounts.
To write off a payable accounts, just find the entry on the screen, click on [details] and then check the [Paid] option to complete the process, like the image below:
At the top of the screen you will have a statement of the total debts already paid and the total open:
And at the left side you will have some auxiliary filters to search your transactions: