You could use the ltrim()
function?
Assuming that the date that you want to strip the 0
of is $date
..
$date = ltrim($date, '0');
Read about it here
If I'm not mistaken, you should replace
$date_start = $rows['date_start'];
$date_end = $rows['date_end'];
With
$date_start = ltrim($rows['date_start'], '0');
$date_end = ltrim($rows['date_end'], '0');