Creates a Drupal Ajax 'remove' command.
The 'remove' command instructs the client to use jQuery's remove() method to remove each of elements matched by the given selector, and everything within them.
This command is implemented by Drupal.ajax.prototype.commands.remove() defined in misc/ajax.js.
$selector: A jQuery selector string. If the command is a response to a request from an #ajax form element then this value can be NULL.
An array suitable for use with the ajax_render() function.
http://docs.jquery.com/Manipulation/remove#expr
function ajax_command_remove($selector) {
return array(
'command' => 'remove',
'selector' => $selector,
);
}