Using the DDMS Perspective in Eclipse, can you delete directories on the phone? You can definitely select and delete files, but I can’t seem to delete any directories. The only way I have figured out how to is at the command prompt:
C:\>adb shell
$ rmdir /mnt/sdcard/Android/data/mydirectory/
I do not know if the android plugin supports the option you are looking for. But I can tell you that it depends on the device also. For example on rooted phones you can use HierarchyViewer and also on the emulator , but this tool will not work with none rooted devices.
You should consider that maybe you are not able to delete because your phone is not rooted. This is for the internal storage, and for external you should consider if your phone is connected with your pc with charge only mode or with disc storage mode. If you connect with charge only mode maybe there will be no-option for deleting files…
Again I do not have you the right answer but I gave you some tips you should definitely consider.