$re = '/\}\}\}(.*)/';
$str = '{"body":{"records": {"time": "2020-12-20T13:28:50.2164144Z","MachineGroup": "Windows 10", "Timestamp": "2020-12-20T13:27:18.6679858Z", "DeviceName": "3242d4e4.dc.democorp.com", "ReportId": 306737}}},"x-opt-sequence-number":159959006,"x-opt-offset":"2713650553292728","x-opt-enqueued-time":1624195823422}';
$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