You will get the following error messages when you try to delete a file/folder which is being blocked by the System or Application Processes running in the Task manager:

Access Is Denied
Sharing Violation Error
File/Folder is being used by applications. Please close the application and then try again.
Solution:

You need to kill the handle. To kill the handle, use Process Explorer from Sysinternals (at URL: http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx)

How to delete the handle:

Run Process Explorer
Go to Find menu > Enter File/Folder name and then click on Search. You will see a list of processes blocking the file/folder.
Right click on the process and then click on Close Handle > Click Ok for confirmation.
Now you can successfully delete the file.