My Passport is Full

My Passport is “full”. How do I select and erase old files? I can select QuickBooks files, but none of the other files on the My Passport drive. Why is that? Also, QuickBooks only keeps 3 backup files so each time I backup the oldest one is erased. I run 4 QuickBooks company files. I don’t want to erase the whole Passport. The “other” files I back up are documents and pictures, but I can’t see those files on My Passport the way I can see the QuickBooks files. As I’m writing this I see a folder called WD Backup.swstor, and inside it is a folder called CRB-20110407, and inside that another, until I come to individual files. Since I backup every hour, if I erase some of these older files am I creating a problem on My Passport? I could select by date modified, say, everything in 2017 and then erase them. Or shouldn’t I be erasing this way?

What backup software are you using?

WD My Passport Ultra.

The Western Digital software version is 1.5.5963 copyright 2016