TAKEOWN

Take ownership of a file (Windows 2003/7/2008).

Syntax
      TAKEOWN [/s Computer [/u [Domain\]UserName [/p [Password]]]]
         /f FileName [/a] [/r [/d {Y|N}]]

Key
   /s Computer
           The name or IP address of a remote computer (do not use backslashes).
           default = local computer.
           This parameter applies to all of the files and folders specified in the command.

   /u [Domain\]UserName
           Run the script with the permissions of the specified user account.
           default = system permissions.

   /p [Password]
           The password of the user account that is specified in the /u parameter.

   /f FileName
           The file name, UNC path or directory name pattern.
           Accepts the wildcard character *

   /a      Give ownership to the Administrators group instead of the current user.

   /r      Perform a recursive operation on all files in the specified directory
           and subdirectories.

   /d {Y | N}
           Suppress the confirmation prompt that is displayed when the current user
           does not have the "List Folder" permission on a specified directory,
           and instead use a default value:
              Y: Take ownership of the directory.
              N: Skip the directory.
           Note that you must use this option in conjunction with the /r option.

If the /a parameter is not specified, file ownership is given to the user who is currently logged on to the computer.

Mixed patterns using (? and *) are not supported by the takeown command.

After changing the owner for a file/folder, you can then assign full permissions to the files and subsequently read or delete them.

“As every cat owner knows, nobody owns a cat” ~ Ellen Perry Berkeley

Related:

CACLS - Change file permissions.
iCACLS - Change file and folder permissions.
ATTRIB - Display or change file attributes.