Using the Sandisk Memory Zone app, when I long-press files that are on a memory card, it does not give me an option to delete them. But the same thing works for internal memory files. The only options for files on the SD card are “copy to internal memory” and “share on facebook”.
After poking around with other file managers, it seems Sandisk MemoryZone copies files from internal storage to /storage/extSdCard/DCIM/Camera/xxx . This makes the standard Gallery app unable to find them (e.g. it still thinks it is at /storage/emulated/0/DCIM/Camera/xxxx ).
BTW I noticed that normal jpg/mp4 files stored on the external SD card from camera/video app are in /storage/extSdCard/DCIM/Camera/xxx .
All I can do from the MemoryZone app is copy the file back to internal storage, and then delete from internal storage. No option to move it back (or delete it), so I am still left with the file on the external SD card as well as a new copy of the photo on internal storage at /sdcard/MemoryZone/Android/data/com.sandisk.mz/files/DCIM/Camera/xxx .
I am having the same issue and have had no luck with a solution.
This might sound silly but I just had the same issue descibed above. I removed the SD card and notice the little physical toggle switch on the physical giftcard was not all the way in the “lock” position nor the “unlock”. After I firmed placed the toggle switch into the “unlock” position, windows explorer allowed me to delete the content.
Hope this helped.