Hello and welcome to Tom's Hardware Forums.
Open the drive in My Computer then from the Tools menu, choose View then tick to "Show Hidden Files and Folders" and untick "Hide Protected System Files", click Apply, accept the warning and click OK.
IIf the drive worked as soon as you first plugged it in, it will almost certainly be safe to delete everything you see that isn't one of your photos but if you have any doubts, post a screenshot or a list of the files back here for advice on what to delete.