I have just signed up to Audible so I was a bit worried about this. However, on my mobile device I went to my membership settings and it said "If you signed up

I have just signed up to Audible so I was a bit worried about this. However, on my mobile device I went to my membership settings and it said "If you signed up for Audible through Amazon [which I did] then you will find the account settings on the Audible site". I navigated there, to "View membership details", and there's a link that plainly says "Cancel membership". Now, maybe the US version is different, and uses dark patterns, but for me it seems very easy.