Closing your accountIf you wish to close your Tumblr account, you can do so at any time on the Delete Account page.
When you close your account, your primary blog will be deleted. You will be removed from any additional blogs may have. And, if you are the only user on an additional blog, the additional blog will also be deleted. If other users are on the additional blog, you will be removed from the blog but it will continue on with its remaining users.
After your account or blog is deleted, your email address and blog URL can then be used on a new account or blog if you wish.
Deleting the primary blogThe only way to delete your primary blog is to close your entire Tumblr account using the Delete Account page referenced above. Your primary blog cannot be individually deleted and the primary cannot be reassigned to another blog on your account.
Leaving or deleting an additional blogIf you have created or joined an additional blog beyond your primary blog, you can leave the additional blog at any time. Click on the title of the additional blog at the top of your Dashboard or under the list icon at the top right of the Dashboard. Then click Members on the right side of the screen. Then click the Leave this blog button.
If you are the only user on the additional blog when you leave it, the additional blog will be deleted. If other users are on the additional blog, you will be removed from the blog but it will continue on with its remaining users.
Leaving an additional blog will not delete your primary blog or your overall Tumblr account.