Hi,

To remove blank space in PDF reports, you need to adjust the 'Top Margin' and 'Header Spacing' in the paper format of the corresponding report.

1- Enable developer mode.

2- Settings > Techincal > Reports.

3- Choose the report.

4- Click on the external link of the paper format.

5- Adjust 'Top margin' and ' Header spacing' in the paper format accordingly.

Hope it helps

Surely this is a simple change. The blank white space at the top of the pdf maybe the header so maybe you also need to change the report definition, like so:
[ I do not have enough Karma to post the picture :/ ]