Currently the username on an existing Snapchat account cannot be changed. The official support document from Snapchat states: 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.
Adding your Display Name on Snapchat is a great way to help friends recognize you when you add them — because let’s face it, usernames aren’t always so easy to understand Your Snapchat Display Name is customizable and will appear to new Snapchatters you add!
To create or change your name, follow the below steps:
Tap in the upper right corner of the Profile page.
Select ‘Name’ under the ‘My Account’ section.
Enter your name and select ‘Save’.
At this time, it’s currently not possible to change your username. Also, if an account was deleted or permanently locked, the username will be no longer available.