Deleting folders give access denied error message on Windows 7, although I am administrator

Solution 1:

You can use unlocker to delete the windows directory. Just install it and it will appear int the right click context menu.

You can also use boot delete which has the ability to delete the files at the boot time.

Solution 2:

I often get access denied errors because the file is in use by a process. I don't know why the error isn't more helpful.

If that's not it, you can try recursively making all the files on the drive writeable with the attrib command:

ATTRIB -R -S C:\ /S /D

(Replace C: with the correct drive, of course)

Solution 3:

The main reason behind this is that the explorer.exe process locks files that are in use, effectively preventing you from deleting them. Usually, these files should not be touched, but sometimes, situations arise when you really need to erase some troublesome ones.

Fortunately, there are a few easy solutions to delete those files.

Solution #1: Kill explorer.exe
Solution #2: Use The Windows Recovery Console
Solution #3: Use unlocker

More details and reference:

http://www.techproceed.com/2014/05/how-to-delete-undeletable-or-locked-file.html