PHP: How can I remove from String the last word?

check this

 <?php
$str ='"Hi, I\'m Gian Marco" will be "Hi, I\'m Gian"';
$words = explode( " ", $str );
array_splice( $words, -1 );

echo implode( " ", $words );
?>

source : Remove last two words from a string

try with this :

$txt = "Hi, I'm Gian Marco";
$str= preg_replace('/\W\w+\s*(\W*)$/', '$1', $txt);
echo $str

out put

Hi, I'm Gian