Removing blank space from delivery slip

[catchop]

Hello. I recently upgraded from 1.7 to 8.1.
I could delete some unnecessary things from the delivery slip header by editing delivery slip tpl files, but there is still meaningless space on the top.
Does anybody know how to remove this space?
Thank you.

[catchop]

Ok, I could handle this myself.

classes-pdf-PDFGenerator.php

I changed this

$this->setMargins(10, 40, 10);

to

$this->setMargins(10, 0, 10);

Now there is less space on the top.