Get out the way, everyone!
I've got the solution!!! (Finally) (This was on the Desktop on Windows 8, but I think it's going to be the same process)
I went through all of the other responses, and they're on the right track, but they're forgetting one key part:
When trying to remove the Windows.old folder, you still have to change the permissions and uncheck the Read-only box (For some of the files) (You may also need to click "ignore all", as there are a few small straggler files that I can't figure out how to remove), but the key is this (This allowed me to delete about 60 of the 74 gigs in my Windows.old folder):
After following the steps to change permissions and all that (As explained in previous user posts):
Under the Security tab, click Advanced
After changing the "Owner" to your account, click on your account under "Permission entries"
Now click the newly available "Edit" button below it
For "Type", set it to "Allow"
For "Applies to", set it to "This folder, subfolders and files"
With all of the basic permissions checked, click the box that says "Only apply these permissions to objects and/or containers within this container"
Now, delete the folder. But don't throw a party just yet. For me, the bulk of the files were still there in number, but the files taking up the lionshare of the space were removed.
For the rest of the files, I used AVG's Shredder, which came with my purchase of AVG 1-Click Maintenance. If you're reading this, it's because the file shredding was a success and I was able to click "Submit reply" AFTER the operation was done. Hence, my PC was A-OK! ... If you're not reading this, it means it went horribly wrong and my PC's been ruined. (I kid you not, this is how I'm attempting to vouch for it)
Method: "Fast delete, 3 repetitions".
PS: It took hours to complete the file shredding. So... heads up. You might want to just select "1 repetition".
PPS: The AVG File Shredder dropped it from about 80,000 files down to a mere 58 files, and from about 14 gigs to 21.8 megabytes.
