If they truly would prefer the UK to leave it’s very simple - they simply have to deny an extension and decline to negotiate a new deal.
They have said they are waiting to hear from the UK of proposed changes to the deal. Nothing yet.
As to denying the extension, that is the mood. However they know that if they deny it, the British will then blame the EU for the post Brexit crash. I can bet that after the Halloween Brexit m you will find lots of posters here blaming the du for British woes.