You can crop pages to remove unnecessary margins.
Select Edit Page Crop Pages to open the Crop Pages dialog. Now select the Crop Margins and a Page Range.
By providing a Page Range, you can crop all pages, or only specific pages (for example a Page Selection).
Instead of entering exact values, you can also move and resize the red rectangle in the preview on the right.
Select Tool Crop Pages and select a rectangular area in the document area. The current page will immediately be cropped to the new dimensions.