You should already be an administrator on your own computer.
Or are you trying to delete something online?
Don't know what happened to your duplicate file question, but here's the answer anyway:http://www.auslogics.com/en/software/du ... le-finder/
Download, unzip & install.
You can search for all file types or just audio, or just video etc.
It will search for duplicate files - of which you'll probably have lots, like me.
Especially when it comes to mps3 - mainly Kiss.
If you have all the albums including compilations, you have songs on the original album & all of the compilations.
It's up to you if you want to keep all albums in their entirety or delete songs you already have elsewhere.