How to Remove Powered By PHPlist Image

Go to the site root, for example /var/www/phplist .
edit admin/sendmaillib.php .
Replace this entire section:

if (!EMAILTEXTCREDITS) {
$html["signature"] = $PoweredByImage;#'<div align="center" id="signature"><a href="http://www.phplist.com"><img src="powerphplist.png" width=88 height=31 title="Powered by PHPlist" alt="Powered by PHPlist" border="0"></a></div>';
# oops, accidentally became spyware, never intended that, so take it out again 
$html["signature"] = preg_replace('/src=".*power-phplist.png"/','src="powerphplist.png"',$html["signature"]);
} else {
$html["signature"] = $PoweredByText;
}

With:

$html["signature"] = "This is my new signature!!";

Or even

$html["signature"] = ""; //I will come back and add one later, maybe..