chown is tool for changing ownership. As root account is superuser type to change ownership to root you need to run chown command as superuser with sudo.
What is “sodo”? :-) I fixed that for you. However, there is one more question: What about changing group? With your command, the file would be still writable for the original owner. I know that OP did not specify what their requirement regarding groups is but you should at least mention it in the answer.
– MelebiusMay 11 '18 at 06:21
root:root
? – qwr Sep 08 '22 at 23:23