Also Briss app, it takes just a few minutes even for the novices (to crop/cut the whole pdf document after its loading, by using cropping boxes/rectangles).
https://www.youtube.com/results?search_query=briss+pdf
https://www.mobileread.com/forums/sh...ad.php?t=83053
Pdf double-page cutting:
https://www.mobileread.com/forums/sh...d.php?t=315771
Pdf margin cropping(removal):
https://www.mobileread.com/forums/sh...d.php?t=330673