title: unrecognized arguments: --username appuser when When I try to run the createsuperuser command
body: <p><strong>My code</strong></p>
  <pre><code>class UserManager(BaseUserManager):
      use_in_migrations = True
  
      def _create_user(self, email, password, **extra_fields):
          if not email:
              raise ValueError(&quot;email field is required&quot;)
          email = self.normalize_email(email)
          user = self.model(email=email, **extra_fields)
          user.set_password(password)
          user.save(using=self._db)
          return user
  
      def create_user(self, email, password, **extra_fields):
          extra_fields.setdefault(&quot;is_staff&quot;, False)
          extra_fields.setdefault(&quot;is_superuser&quot;, False)
          return self._create_user(email, password, **extra_fields)
  
      def create_superuser(self, email, password, **extra_fields):
          extra_fields.setdefault(&quot;is_staff&quot;, True)
          extra_fields.setdefault(&quot;is_superuser&quot;, True)
          extra_fields.setdefault(&quot;username&quot;, None)
  
          if extra_fields.get(&quot;is_staff&quot;) is not True:
              raise ValueError(&quot;Superuser must have is_staff=True&quot;)
          if extra_fields.get(&quot;is_superuser&quot;) is not True:
              raise ValueError(&quot;Superuser must have is_superuser=True&quot;)
          return self._create_user(email, password, **extra_fields)
  
  
  class User(AbstractUser):
      username = &quot;user&quot;
      email = models.EmailField('email adress', unique=True)
      USERNAME_FIELD = 'email'
      REQUIRED_FIELDS = []
  
      class Meta:
          db_table = &quot;USER&quot;
  </code></pre>
  <p>Note that my user must only authenticate with his email and password.
  Terminal outpout<br/>
  usage: manage.py createsuperuser [-h] [--email EMAIL] [--noinput] [--database DATABASE] [--version] [-v {0,1,2,3}] [--settings SETTINGS] [--pythonpath PYTHONPATH]
  [--traceback] [--no-color] [--force-color] [--skip-checks]
  manage.py createsuperuser: error: unrecognized arguments: --username appuser</p>