What Happens if You Delete Your Tumblr?by Laurel Storm
If you've lost your enthusiasm for reblogging animated GIFs and scrolling down an endless dashboard, the best way to quit cold turkey is to delete your Tumblr blog entirely. Once you've done so, however, you can't reverse the process -- and since the result of this action changes depending on whether you are deleting a primary or secondary blog, you should take care you don't accidentally delete more than you intend to.
When you delete a Tumblr blog, everything that was published on it disappears. However, that doesn't mean your content is entirely gone from Tumblr. If other people have reblogged something you posted, the content you created also appears on their blogs and will not be removed, regardless of whether your blog is still active. The only way for your content to disappear from somebody else's blog is if that person removes the posts that contain it or also deletes his entire blog.
Deleting a secondary blog only affects that blog and its contents. All content posted on that blog will be lost when it is deleted; the blog URL will be freed and become available for anybody to register. Keep in mind, however, that you can't delete a group blog until all its members have left or have been removed. If you don't remove everyone, ownership of the blog will simply pass to another member. If you have administrator access to the group blog, you can simply remove all members from it and then delete it; if the blog is still active, however, it's generally polite to ask members if they want to continue it rather than deleting it outright.
Deleting your primary blog affects your entire Tumblr account. If you choose to go ahead with the deletion, you will lose everything you have ever done on Tumblr, including your secondary blogs and their content, the list of people you follow, and your Tumblr account itself. The URLs of all your blogs will be freed up and become available for anybody to register; you will also be able to register a completely new account using the same email address.
Any purchases you have made on Tumblr will be lost when you delete the blog it is associated with. If you want to transfer premium templates you have purchased from the blog you plan to delete to another, you need to get in touch with Tumblr staff before deleting the blog. If you delete your account altogether, you will permanently lose any Tumblr Credits you may have.