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My backup program filled half of my backup disk with backup copies of windows files owned by "trusted installer", and for which only "trusted installed" has delete permission.

These files seem to be nearly impossible to delete. I've found that the suggestion to take ownership of the files and then assign all access permission works individually, but not recursively to a directory.

We're talking millions of files here, so I need a bulk delete program that will cope with hierarchies for which only "trusted installer" has delete access.

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There's a "Replace owner on sub containers and objects" checkbox in owner change dialogue. With this checkbox checked, it will change owner of all subcontainers and objects within the tree.

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changing the owner is insufficient, as the only owner who could delete the files is "trusted installer" – ddyer Jun 26 '13 at 16:01
@ddyer The owner has some implicit rights and can change the file's access control list to give himself full access. – Werner Henze Jun 27 '13 at 7:53

Here's the best partial answer so far. Using an admin shell,

icacls "Directory" /grant Administrators:F /C /T /Q
rmdir /s "Directory"

This pair took a total of 24 hours to change properties and delete about 20 million files from an external usb drive. Leaving behind only some "users\all users\" directories for which there seems to be no access at all. I'm still looking for a way to dispose of these.

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Why not simply attach the USB drive to a Linux machine (or use a Linux LiveCD/USB) and get rid of what you want without Windows permissions getting in the way? – Karan Jun 27 '13 at 23:55
If I had one handy, and linux can handle ntfs, I might have tried it. Not a good windows procedure! – ddyer Jun 28 '13 at 5:17
Linux can most definitely handle NTFS since it includes ntfs-3g. – Karan Jun 28 '13 at 16:29
"Use Linux" is one solution to a lot of windows problems :) – ddyer Jun 28 '13 at 17:21
Heh, well maybe. :) In this case it would certainly be faster since you can directly delete the files instead of waiting for the correct permissions to propagate, then wait for the files to be deleted. – Karan Jun 28 '13 at 17:23

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