This article explains how to change your Skype Name. Instructions apply to all Skype platforms, including Skype for Windows and Mac, Skype on the web, and the Skype mobile app.
How do I change my Skype username?
Your Skype display name is different from your Skype username. You can change your display name at any time and it is what other Skype users see when they communicate with you.
Your Skype username is the email address used to create your Microsoft account, a result of Microsoft acquiring Skype in 2011 and requiring a Microsoft account to sign in to Skype. As such, you can only change your Skype username or ID by changing the email address associated with it and your Microsoft account.
If you signed up for a Skype account before Microsoft acquired Skype, you're probably using a non-email-based username that you can't change unless you create a new account. In that case, you'll lose your existing contacts.