code: def delete_permission(self, vname, username):
          
          vname = quote(vname, '')
          path = Client.urls['vhost_permissions'] % (vname, username)
          return self._call(path, 'DELETE')
docs: Delete permission for a given username on a given vhost. Both
          must already exist.
  
          :param string vname: Name of the vhost to set perms on.
          :param string username: User to set permissions for.