Additional Files? How do I access them?

I have a WD 4TB My Book. I only have about 1.1 TB of saved pictures and Videos however I am out of space. Upon looking at the device target destination gauge, it show in a light grey “additional Files 2.9 TB”. I cannot access them to see what they are and delete them. The My Book Icon is showing under my desktop and also separate as a stand alone in my directory. I’m not sure how to free this space up.
Any suggestions?


Additional files, are located on your external drive but they were not uploaded by WD Smartware. Probably, they were copied to the drive manually (Copy and paste) Or they were uploaded by a different software.


Any way to access them and delete them?