Close your Tumblr account
There are 2 ways to delete your Tumblr account, depending on whether it's connected to your Yahoo account or not. To find out which way applies to you, sign in to your Tumblr account, go to the Settings page, and look for a "Delete account" button.
If you see a "Delete account" button, follow the directions on the Tumblr Help site to terminate the account.
If you don't see a "Delete account" button, then your Tumblr account is linked to your Yahoo ID. You must close your Yahoo account to delete your Tumblr account.
If you close your Yahoo account - you'll also close all your Yahoo services, such as Yahoo Finance and Yahoo Mail.