I had to delete downloaded ISO files after installation of SQL on new server windows 2012. Most of files were deleted, but one ISO file keeps telling 'Access is denied'. I looked at properties/security, the owner box is empty, looks like permission problem. I went up one more level up in the directory, tried to take ownership in both in the properties window and through CMD as administrator, still can't take ownership of the ISO file.
There are some people suggests to download unlocker to delete the file, but want to know how I can resolve this problem without any 3rd party software.