Deleting "undeletable" files in Vista

"You'll want to first take ownership of the files, which is easiest when you add Take Ownership to the right-click menu.

Once you've done that, you can do one of the following:

Use Unlocker to remove whatever is locking the file, and then delete it.
Use Boot Deleter to delete it when you reboot.
Try and rename the file, sometimes you can rename them when you can't delete them. Once you reboot, you can delete it.
Try and delete it from safe mode.
Delete it from the command prompt, usually safe mode works the best."

Try taking ownership of the files and then deleting them.

"Another alternative is using a Linux Bootable USB stick. This is especially convenient if you already have one lying around. Sometimes taking ownership of files does not work. The nice thing is that this also works if you cannot take ownership.

Step by step:

Create a Linux bootable USB stick (for instance ubuntu: http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-windows )
Boot from the USB stick
Navigate the folders and delete everything you want."

"Sometimes, especially with external drives, this can be simply resolved by changing the ownership properties in the security tab of the properties of the file or folder in question. While this is, by far, the easiest solution, for more problematic situations, it may not always work.

Right click on the file or folder in question
Choose 'Properties'
Click on the Security tab
Click on 'Edit'
If 'everyone' is not present Click on 'Add'
Type 'everyone' (without quotes) and press OK
In the lower part of the dialog, choose 'Full Control' and then press
OK

Try deleting again.

Edit:

Also, sometimes it is necessary to do this process with the parent folders containing the files in question."