Open the PDF in a PDF editor (Adobe Acrobat, Preview on macOS, or an online PDF editor)
Select the “Crop” tool (or “Edit PDF” → “Crop”)
Drag the crop box to the area you want to keep
Adjust the crop box edges if needed
Apply or confirm the crop
Save the cropped PDF (Save As to keep the original if desired)
If needed, re-open and verify the crop area is correct
Export as a new PDF if your editor requires it for the crop to be finalized