<?php
// IF ONLY CHARACTER IN STRINGS
$str = "Hello PHP";
echo str_replace("PHP","",$str); // its remove PHP From string
//Output = Hello;

// IF NUMARIC OR CHARACTERS IN STRING AND YOU NEED ONLY STRING
$strInt = "124Peter56";
echo $words = preg_replace('/[0-9]+/', '', $strInt); // it remove integer from string
// Output = Peter;

// IF NUMARIC OR CHARACTERS IN STRING AND YOU NEED ONLY INTEGERS
$strInt = "124Peter56";
echo $res = preg_replace("/[^0-9]/", "", $strInt ); // It Remove all string 
// Output = 12456
?>