Yes you can delete Images but I do not suspect you can do them all at once.
I recommend you query the Mediastore to get the _ID of all Images and then loop through the list and delete them. Here is some sample code but i'm sure it can be better optimized. This code is filesystem agnostic so it should work anywhere.
Code to get list of all items on Mediastore.Images
List<Long> mediaStoreIds = new ArrayList<Long>();
Cursor c = context.getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, new String[]{BaseColumns._ID}, null, null, null);
if (c != null) {
final int id = c.getColumnIndexOrThrow(BaseColumns._ID);
c.moveToFirst();
while (!c.isAfterLast()) {
Long mediaStoreId = c.getLong(id);
mediaStoreIds.add(mediaStoreId);
c.moveToNext();
}
c.close();
}
Then to delete, well you could do that right in the original loop or loop through the arraylist, but here is how to delete:
context.getContentResolver().delete(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, BaseColumns._ID + "=?", new String[]{Long.toString(mediaStoreIds.get(i))});