Once you have chosen a URL for your designer profile, it can’t be changed. You can, however, change your designer name in your design studio. When people navigate to your design studio, the URL will always stay constant, but the display name can be changed.
To change your designer name, login to your designer profile and click "Edit Your Designer Profile." Type in a new designer name and be sure to click "submit" and voila! Your new name will now automatically appear and update on all sections of the Minted site.