Are you using the Administrator account on your computer?
Do you have any security software on your computer? If so, I would recommend disabling it.
If you are and have tried the steps in trouble installing iTunes KBase posted above, I would recommend that you (trying again after each step):
1. Empty your trash and then open the folder and delete all you can from it
2. Create a new admin user on your computer and then try deleting the file there. If you are able to delete it there, then you can log off of the new user and delete the user account and its files, and then be done.
3. Try a Microsoft based resource on troubleshooting permissions issues, ie: (windows 7) http://www.addictivetips.com/windows-tips/windows-7-access-denied-permission-own ership/
4. Boot your computer into Safe Mode in case a process is (or thinks it is) using it. (You can find directions here --> http://www.computerhope.com/issues/chsafe.htm#03) And then try to delete the file.
5. This thread has some additional ideas and a possible workaround - http://www.tomshardware.com/forum/5932-63-logged-admin-account-delete-anything
Workaround 2 - Rename the file, then it won't matter to iTunes or anything else.
6. IF this all fails, I would either call the manufacturer of your computer to assist with the permissions issues, OR attempt to use a third party product to remove the file...I would suggest Unlocker, at http://lockhunter.com. You can of course find alternative programs on Google search.
I hope this helps! Good luck! 😉