How to Change Your Tumblr Blog to One of Your Saved URLsby Laurel Storm
Combine the fact that Tumblr lets you create as many blogs as you want and the fact that you can change a Tumblr blog's URL at any time, and you get the practice of URL saving -- creating new blogs simply to reserve URLs you like just in case you want to use them in the future. Switching your blog to one of your saved URLs is somewhat risky: if you aren't quick enough and the URL is distinctive and desirable somebody else might take it. There is, however, a way to minimize this risk.
Navigate to your Tumblr dashboard. Click the "Gear" icon and, from the list of blogs, select the blog with the URL you want to use. Scroll down to the bottom of the page so the button labeled "Delete [blog URL]" is visible.
Open a new browser window or tab and navigate to your Tumblr dashboard. Click the "Gear" icon and, from the list of blogs, select the blog whose URL you want to change. Delete the current URL from the "URL" text field and replace it with the saved URL.
Open a new browser window or tab and navigate to your Tumblr dashboard. Click the blog menu and select "Create a New Blog." Type a random title in the "Title" field and the URL for your current blog in the "URL" field.
Switch to the first window or tab and click "Delete [blog URL]." Immediately switch to the second window or tab and click "Save." Immediately switch to the third window or tab and click "Create Blog." Your blog is now using the URL you were saving and you have a new blog using its old URL so nobody can take it.