Windows 7: Deleting File Permissions Problem

I have an external NAS drive that over the years I have dumped files to and backed up drives to.
I now want to do some housekeeping and delete old folders but for example the Local settings folders/files that I have dumped off for other family members wont allow me to delete them.
There are hundreds of old temp internet files so need to be able to change permissions for all files etc. and currently I can only think of copying disk (2TB) then formatting and bouncing back only the files I want, long process :-(

Any advice much appreciated

See here: Take Ownership Shortcut

Just right click on the file or folder you want to delete and select Take Ownership.