How do I cancel "kindle unlimited?" - Tablets & eReaders

Sign in to Amazon.
Click on "your account" link at top left of page.
You will see Kindle Support section to right side of next page.
Scroll down to "Manage your content and devices" and click on that.
On the next page click on "settings" link.
On next page scroll down until you see: Kindle Unlimited Settings.
Click on "Manage your membership".
On left side scroll down until you see: Cancel Kindle Unlimited Membership

There you go. Just click on the link and cancel your membership.