Best answer by Navid
You can change your Display Name and Profile URL by going to your profile: http://soundcloud.com/you and hit the 'Edit' button on the right, under your header image. To change your URL, click the little pen icon that appears beside your URL, like in this image: http://cl.ly/image/0D3b1l2G0L3V
Please note that if you change the URL for your profile, any links and embeds previously posted to third-party sites before August 2010 will be broken. Embeds posted after August 2010 will still play your sounds but, if the listener clicks through to the SoundCloud page, they will be directed to an empty page.
You can read more about how to change your profile image on our help center:
Hope that helps!