Have you ever run into a situation where you wanted to delete a file,
but Windows simply wouldn’t allow you to do it? Personally, these
things happen to me all the time, especially when I’m at a client’s
house trying to get their machine clean of malware. Have you ever
tried deleting a locked file using common windows commands? If so,
then you’ll know that this is just not possible.

if yes, you can try special tool Long Path Tool
http://HowToDeleteFile.com

[Sifou]

You can also use Unlocker, which has saved me and my team a couple of times when deploying software, services, etc... and I have even seen people using it on production environment (not that I recommend it but.....).

the following link praises this software (Unlocker) and compares it to similar software:

http://www.emptyloop.com/unlocker/

Sifou