I have a folder in one of my partitions with this name; 6a004149b189707931f3b5
Windows won't let me delete this folder as it claims I need permission from Network Service; what is this folder ?

Sometimes these folders are created during the installation process. They can safely be deleted but occasionally this can be difficult. You might try deleting the folder from a command shell running as Admin.

This folder may be part of an update installed by Windows or a software like .NET framework which creates this folder to create a temporary access for it's extracted files used during installation.

Best is to set it as "Hidden" and leave it alone.

If you really want to delete it, then I leave the after-effects for you to ponder on, but you can install and use the software "Unlocker" (Google it to get the download link as well) and proceed with deleting the folder (you can use youtube here to see how to use it properly).

In my experience, Microsoft has a poor record of cleaning up after itself when installing updates. I have never run into a problem deleting these leftover folders. Leaving them present but hidden just clutters things up.

Hi, you can try third-party software like "lockmaster" or "Take Ownership" to unlock the files being used or take the ownership of the files in order to modify/delete them. I suppose that in your case, "Take Ownership" should help you.

   Network Service sounds suspiciously like Trusted Installer which is basically you and some install disc.  Network Service is probably some app that you installed while online.  An Administrative Command Prompt may help but probably won't by itself.  Like most things the real work in any Windows install is done in DOS (Disk Operating System).  Use the DOS app Attrib to find out what attributes are associated with the file/folder.  Many that are hard to be rid of have the attribute "S" for system.  Remove the "S" and add "A" for archive.  That should enable you to be rid of the file/folder.  If it reappears after an apparent successful DELETE its probably because of a residual notation in your REGISTRY.  The resolution then is simple, find the notation in your Registry and delete it.  In any case, before you actually delete it find out what, if anything, is actually in it.  Deleting it may require a Safe Mode boot.
   While drastic this WILL usually work.  Backup and/or copy everything else off of the partition and format the partition, then, reload the partition.  Be careful, backup is notorious for losing the odd setting that you usually take for granted, *.ini for example.