Permanent crop tool that actually removes cropped content. Masking content does not work for PDFs that need to be later uploaded online. It botches thumbnail creation and causes files to be unnecessarily large.
Sorry fot the inconvenience caused to you.
You can crop the file by following below steps.
1) Open a pdf
2) Click on edit pdf
3) Select option Crop Pages
4) Now select the desired area and click enter
5) Now you can select your desired settings for crop, click ok and save your file.