Try applying the steps outlined for taking ownership of the folders starting at the lowest level of the branch:
\Folder\Folder\backup.zip
Select the files inside the folder and right click/properties ... permissions, advanced, etc.
Repeat by selecting the folder containing those files
Repeat for any folders and files at the same level within the top level
Repeat for the parent folder, typically \Windows Live OneCare backup\ or similar.
Once you've applied the permissions successfully, start at the file level deleting the files, then the folder, then finally the empty parent folder.
Failing that, contact support for help.
How to reach support (FAQ) - http://social.microsoft.com/Forums/en-US/onecareinstallandactivate/thread/30400b52-7f26-4ba0-bc18-17e305329d90
-steve
Microsoft MVP Windows Live / Windows Live OneCare, Live Mesh, & MS Security Essentials Forums Moderator