Pamac already had a reported bug in older versions, therefore I felt like swimming in the unknown. After somewhat unnecessary “panic-mode” steps in order to prevent any damage to my Manjaro system prior to my first orphan removal, I finally succeeded to clean my system by using the above command. Overall, I needed to review the list one-by-one and when I identified the packages I wanted to keep, I did the following (before removing the orphans) to mark them as explicitly installed:
$ sudo pacman -Rsn $(pacman -Qqdt) # Press n
$ # Check your packages carefully and write down those ones that you've installed manually!!!
$ sudo pacman -D --asexplicit atom-editor-bin drawio-desktop-bin viber # The packages that you need
Creating backups is important and this is the routine I relied on for this particular purpose before I removed anything:
BACKUP:
pacman -Qqen > pkglist-repo.txt
pacman -Qqem > pkglist-aur.txt
RESTORE:
sudo su
for x in $(cat pkglist-repo.txt); do pacman -S --needed $x; done
yay -S --needed --nouseask $(< pkglist-aur.txt)
After the pamac command, I restarted Manjaro and used the aforementioned script that additionally cleared 234M of space.
I have freed approx. 1.5G of my disk space by removing those orphans and after some testings, the system seems stable. This was my very first experience in removing the orphans, so I apologize if I raised some eyebrows out there. 
Thank you for all of your patience and support! 