How to decline an application

Hello. I agreed to do a pet sit with someone, they accepted, and then I realised that I had misread the dates. So I told them, they were very understanding, and told me to just decline the application.
I have spent 30 m intes trying to find a way to do this, but just keep going round in circles.
Can someone help please, as I am still currently down to do said sit on the site.

Thanks.

@Simon_Downes

If this is already a confirmed sit then only the homeowner can cancel it . They do this by selecting unconfirm sitter.