Permission to delete C:\users files (windows 7)?

I do not have an account on my computer that allows me to delete/change many C:\users accounts. The guy who built the computer gave me some possible passwords (two years later).

I still don't understand how to allow any of my three accounts to access/delete/change locked (?) files.

How do I give an account permission to access/delete/change any folder or file on my C: drive?

Yami2014-11-04T16:38:52Z

If you don't have access to an admisistrator account I don't know what to tell you. You could remove any stored passwords on the computer using http://pogostick.net/~pnh/ntpasswd/ or try out Mint Linux