Exactamente como dice Yop289, quedaria asi:
Código PHP:
<?php
if (count($_POST['delete']))
{
include("scripts/conexion.php");
foreach ($_POST['delete'] as $id)
{
$sql=mysql_query("DELETE FROM usuarios WHERE id=$id");
}
echo "<script> alert (\"Usuario(s) eliminado(s)!\"); </script>";
echo "<script language=Javascript> location.href=\"consultausuario.php\"; </script>";
}
?>