How to Permanently Delete or Deactivate Pinterest account.
To Deactivate your Pintersest account, login to pinterst and click your username in the upper-right corner, and select Settings from the drop-down, scroll to the bottom of the Settings page and find deactivate account click the Deactivate Account button.
Here is the quick link https://pinterest.com/settings/
You will see a pop-up asking you to select any reason for deactivating your account, select any and click on deactivate account. After you deactivated your Pinterest account, Pinterest will preserve your username and password, you can reactivate your account, all you need to do is log back in.
To permanently delete click on Permanently close my account from the deactivation menu.