I noticed that my pictures were taking up over 5 GB of my memory. I only have about 50 photos on my tablet. Infound out that my online photo albums were downloaded from Facebook onto my tablet. I can't delete them.
Did you try to delete going in through "my files"? I dont use face book, I know its shocking, but are there any settings related to facebook that tell it to keep the photos on the device versus uploaded to the site? Just a thought.