HI With the icacls name-file command, the unknown users (with their SID) do not appear. Why? So, how do I remove, from the files or folders, these unknown users that have a check on these files/folders? THANKS BYEBalubeto

What's the command line you used? Is it the system file? You may try the following syntax: icacls /remove :g <SID> Dale

What's the command line you used? Is it the system file? You may try the following syntax: icacls /remove :g <SID> Dale I installed Windows 7 Home Premium on an NTFS partition. When I run, from the command prompt, the command "icacls file-name", all users, who control this file/folder, appear, but, then, appears a sentence indicating that a user can not be displayed because, in the registry, his name no longer exists. Unfortunately, his SID does not appear and therefore I not can apply your command. So, how do I delete this unknown user from these files/folders? THANKS BYEBalubeto

I tried with the icacls command but when it parses a file that has an unknown user among its permissions, it does not display the SID of this user but the message "is not been no mapping between account names and security ID (SID) " is displayed. So, you have some ideas on how to solve this problem? THANKS BYEBalubeto