There are some PHP functions available depending on what you need, but generally a quicker way would be:
$arrayToReplace = Array('%', '@', '/', '"', '!'); // Whatever in here;
foreach($arrayToReplace AS $value) {
$originalText = str_replace($value, '', $originalText);
}
If you've got a reasonably recent version of PHP you can even shorten this to
$originalText = str_replace($arrayToReplace, '', $originalText);