Yes, you can change your primary blog on Tumblr. To do so, follow these simple steps:
Log in to your Tumblr account. Click the “Blogs” tab at the top of the page. In the “Blogs” section, click on the blog you want to change as your primary blog. On the right side of the page, under “Settings,” click on “Primary Blog.” In the “Primary Blog” section, under “Blog Name,” type the new name for your blog.
(For example, if you want to change your primary blog to “My New Blog,” type “My New Blog” in the “Blog Name” box.) Under “Description,” type a brief description of your blog. (For example, if you want to change your primary blog to be about fashion, type something like “A blog about fashion and lifestyle.”) Click on the “Save Changes” button.
Congratulations! Your new primary blog is now set up and ready to go!.