"File Access Denied" to a .TMP file, even to administrator

Hi there:

While writing in a .xls file, a .TMP file has been inadvertently created:
"original_filename.xls~RF17c85d1a.TMP"
Although I'm the only user, and appear as the administrator, Windows won't let me delete the file, nor make any changes to its security and permissions settings, nor change its ownership.

Either the relevant check boxes are locked or an error message pops up:

File Access Denied
You need permission to perform this action.
You require permission from computer administrator to make changes to this file.

How can I delete the #### thing?
Incidentally, my temporary System files are hidden by Windows Explorer View settings.

Thank you

Have you tried it from Safe Mode?

Alternatively, give Unlocker a try.

First, install and run CCleaner Free, see if that cleans up this and other temp files.

If not, boot to Safe Mode by pressing F8 during boot, as soon as the manufacturers logo appears (press every second or so.).

Login normally.

Open Computer and navigate to the .tmp file you want to delete and try deleting it. If it doesn't show up, you need to Show hidden files:

Open Control Panel then Folder Options and click on the View tab.
Select "Show hidden files and folders"
Uncheck "Hide extensions for known file types"
Uncheck "Hide protected operating system files (recommended)" (click Yes when prompted)
Click Apply and OK

Then use Computer and navigate and delete. If it still doesn't work, install Unlocker to delete the file.