I read about Prime being hard to cancel several times now. It's not harder than any other membership. It feels weird defending Amazon, but just go to your Account, you will see a large card right at the top saying Prime. Click that, on the next screen, again, right at the top it says "Membership. Update, cancel, and more". Click that and it will open a large popup with the End membership button.

Yes, it's true, that on the next screen it will tell you how much you saved using Prime and will offer to look at other plans or to continue cancelling. So this screen is sort of a dark pattern, I guess. Even then, privacy-oriented companies like Proton show a similar upsell screen on cancellation.

Overall Prime cancellation is very straightforward, compared to scummy companies that require you to email or call them to cancel membership. Unless the (unreasonable) expectation is that the CANCEL PRIME button should be front and center on every page on amazon.com. And clicking it should immediately cancel the membership without any confirmation.

Edit: the shaming element of the cancellation process was removed by Amazon long time ago.