My external hard dive is full and there are a lot of files that have been backed up that should be in the trash. How do I remove selected files rather than clearing the whole thing? I will purchase another seagate free agent go flex when I am assured that I have control over what I can keep backed up and what I can delete. This external hard drive has been trouble free but I don't much about it aside from connecting it and setting it up. Thank you Humannbeing