1. Click on "Help" tab
2. Go to Support
3. Start new Discussion
4. Select category to Services(private) and type something similar to this:
It will take some time for the Admins to respond, so you'll have to wait patiently until they send you a PM in the DF support website.
(Notice: This is also the same way as getting Ghost Ammo)
Also keep in mind that you'll need to have 1000 credits in your account to change your username.
