$re = '/:\K.+:/';
$str = 'gejoxloq@gmail.com:DefeatedHarlequinSalamander:79c0d5007090af1832e9f3995b01513e:OTM4NTI5MzExNzOdjnDk2.YfrnuQ.KCDRHpx1E-YDSway-76SfkwivnQ';
$subst = "";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php