In 2009, when Facebook introduced custom URLs (also known as vanity URLs) for your profile and fan pages, Facebook claimed that the custom URL you choose can be only set once. Once the custom URL (example http://facebook.com/MadScientistSM) has been set, it cannot be changed to another URL. But it looks like Facebook is giving a second chance to people who didn’t wisely choose their custom URLs for their profile page.
To change the custom URL of your profile page, simply go to Account –> Account Settings –> Username and click the link change. You will be now able to change your username for your profile page.
If you want to change the custom URL for your fan page for a second time, then you may be out of luck. I haven’t figured out how to do it.
Transferring the Profile Page URL to Fan Page URL
When Facebook introduced custom URLs last year, I secured the custom URL (MadScientistSM) for my profile page as I couldn’t secure it for my fan page. In 2009, you should have at least 100 fans in order to get a custom URL for your fan page. Now this number has been reduced to 25.
Given that Facebook allows me to change the username for a second time, I was able to change my existing username (MadScientistSM). By changing my username, I was able to release the URL MadScientistSM.
Soon after I changed my username, I went to http://facebook.com/username and set the URL techthinker as the URL for my Facebook fan page!
The ability to change username for a second time gives you a chance to trade usernames with others. It also gives you a chance to transfer your profile page URL to your Fan Page URL.
(Courtesy Of TechThinker)