When printing, previewing and saving as PDF, yes. In Browse Mode, no.
Select the portal while in layout mode and set the portal to slide up | also resize enclosing part. (Found on position tab in the inspector.)
This will eliminate empty rows but all rows will remain the same height. (What you show above, is not possible in a FileMaker portal where you have the same row adjusting in height to fit the number of rows of text inside the fields.)
You can get greater flexibility if you set up a layout based on the portal's table. Fields from your related parent record can be added to this layout in headers, footers, grand summary, and sub summary parts to produce the report you need. With this approach, you can set your individual portal recors to slide up to adjust to the number of rows of text, but you'll still have trouble with the field borders that you show here.