<?php

// 3 examples
$text1 = 'Hello world (see below).';
$text2 = 'Lorem ipsum (there is a picture here) world!';
$text3 = 'Attack on titan (is lorem) great but (should not be removed).';

// regex
$regex = ''; // ??

// preg_replace strings
$text1 = preg_replace($regex, '' , $text1);
$text2 = preg_replace($regex, '' , $text2);
$text3 = preg_replace($regex, '' , $text3);

echo $text1 .'<br>';
echo $text2 .'<br>';
echo $text3 .'<br>';