<?php

$str = 'a\bc"1\'2d4/e/fgh\\\abc\\//a"bandan\'and';

echo $str.'<br>';

$search = array(1, 2, 3, 4, 5, 6,'*','$','\\','/',"'",'"',"and");

echo str_replace($search, '', $str);//abcdefghabcaban

echo '<hr>';

?>