I paid a supplier invoice netted with credit note correctly: however the supplier is still showing as a credit: how do I remove this?

Hello there, madeline-roberts,

Let me help share information about suppliers credit balance.

In your case, to further isolate the issue, check if there were still unapplied credits which causes credit to customers balance.

Here's what you'll need to do:

1. Go to Sales in the left navigation menu.
2. Go to the Customers tab, then click the name of the customer.
3. In the Customer page, click on the Transaction List.
4. Click the Filter button, then choose Credit notes for the type.
5. Click Apply.

From there, you'll able to see the Unapplied credits which causes the credit balance of the customer.

That's it! For future reference, here's a great resource that you can check: Enter and apply a credit note or delayed credit.

If you have further questions about customers credit balance, please let me know. I'm always here to help. Have a great day!