I wanna to freeze a folder in red hat so nobody (even root) can not add file into the folder or change files that exist in the folder already, i tried to make folder read only but this does not work and root user can add files normally as before, please somebody help me to solving this problem.
No. By design, in Linux, root ignores existing permissions on all entities. However, what you can do is encrypt files so that they can't be read and can't be modified by those who don't know the key. You can't prevent new files from being added, but with both encryption and decryption keys private, you can easily verify if any file is valid.
This also means you can't have either key on your computer!