Change Facebook Page User Name and URL

When I am creating Facebook fan page for W3Technology.It created random url like below this

https://www.facebook.com/pages/W3Technology/153220521377449‎

I do not want random url I want to change url Like below this

https://www.facebook.com/W3Technologyofficial
‎

Suppose people have more "Likes" your facebook fan page,we can able to change your url without loosing them

Now,I explain how to change Facebook Page UserName and URL :

1.Login to your Facebook account that is pages admin

2.Type into your url bar - www.facebook.com/username

3.Following page will display like this




4.If you want to change your username Click --->Edit username

5.If you want to change your page name : Select which pages url you wish to changes .

6.Type the url  you would like untill you find one that is available.