At some point, you might decide it’s time for a username refresh. Spotify makes it super simple. If you’re on the desktop app, just click your username on the top-right header, select “profile” from the dropdown menu, then select your current name. A field should appear where you can populate a new name. Hit save, and you’re all done.
If you’re on the mobile app, make sure you’re on the “home” tab before hitting the settings icon that looks like a little gear. Tap the “edit profile” button, type in your new name, then press save. That’s all there is to it.