how can you change your snapchat username?
According to Snapchat support, you can not change the username of an existing user This is bad news but nothing is impossible. The good news is that you can simply remove the current username and create a new username with the name you want.
to remove your snapchat username show this video:[alert-success]or you can see the full post: how to delete your snapchat account[/alert-success]
This is the text of what was written on the site of Snapchat about changing the username:
For security reasons, it is currently not possible to change the username for an existing account. If you wish, you may delete your account and create a new one with a different username.