In Finder and Terminal — can not delete a folder, (Error = "Directory not empty")
Hi David and Igor — Issue is resolved, but the solution is not something I'd have considered as even being a relevant one, but I wanted to post it here for whoever this might help in the future (as well as put closure to Igor's / Dave's possible curiosity. And once again, thank you guys for all your suggestions.

For a completely different (separate) reason, I logged out of iCloud (on the Mac — not iPhone or iPad). Went through all the usual items (saved my stuff locally), etc., and somehow - when I logged back in, my trash was empty!

One of the things I wanted to share here with this forum / group, is that I learned something I hadn't known previously: Since the incarnation of iCloud, the PATH to my "Trash" folder no longer is (what it's always been)... /Users/myHomeDir/.Trash — instead, it was now: myHomeDir$ /Users/mike/Library/Mobile\ Documents/com\~apple\~CloudDocs/.Trash/  — and I only learned this after searching that first path several times, both while logged in as myself (in Terminal), but also, while booted into Single User mode. Nowhere in either of those means, was my Trash directory located. But when I drag and dropped that  from my trash... to my terminal - that was the path it gave. (and confirmed this while logged into Single User).

Go figure... sorry for the lengthy post, but wanted to be thorough in my resolution for anybody this might help. But all this said, I guess that since the advent of iCloud, this is now the default location for everybody's Trash folder? This presents an entire new thread of questions for me (Apple's implementation of their folder hierarchy, since iCloud) - but no questions specifically at the moment.