Sometimes when I scan, there is a lot of empty space around that I would like to delete using Adobe Acrobat DC.

Currently, the cropped content is only hidden, and it increases the file size. This feature was also discussed here:

https://community.adobe.com/t5/acrobat/discarding-cropped-area-with-adobe-acrobat-pro-dc-2018/td-p/10407421?page=1