如何从数组中删除键？

Question

I have these arrays.

'tickets' => 
array (size=2)
  1 => 
    array (size=19)
      'ticket_id' => 1
      'ticket_event_id' => 158
      /* some good values */
  4 => 
    array (size=19)
      'ticket_id' => 4
      'ticket_event_id' => 158

And I would like to unset values 'ticket_id', 'ticket_event_id' and array key. I used this code

foreach ($event['tickets'] as $ticketId => $ticket) {
            $ticket['ticket_id'] = null;
            $ticket['ticket_event_id'] = null;
            $event['tickets'][$ticketId] = array_replace($event['tickets'][$ticketId],$ticket);
        }

But I have no idea, where and how I can put some code to unset array key.

I would like to recive array in this form

null => 
    array (size=19)
      'ticket_id' => null
      'ticket_event_id' => null
      /* some good values */
null => 
    array (size=19)
      'ticket_id' => null
      'ticket_event_id' => null