Actual account deletion is not possible at this time.
If you wish to start over because you want to play as a different class, you can tubmail a moderator and explain your desire. We can ban your account and have you start again under a new class. If you’d like to reuse your e-mail address, be sure to change your current one before tubmailing him.
Note: We’re more likely to allow you a restart if you’re around Level 5 or lower. Also, we would frown upon a player requesting to go through this process multiple times.
Note: If you wish to start over because you don’t like your build, you can simply use haxlrose to reset your stats.
If you can't find your problem in the knowledge base, please submit a bug report.