On Friday 20 March 2015, Gene Heskett wrote:
> On Friday 20 March 2015 13:38:37 Gerhard Zintel wrote:
> password.  But the only way to get rid of a root password is a bare
> metal reinstall.
>
and from 

$ man passwd


       -l, --lock
           Lock the password of the named account. This option disables a
           password by changing it to a value which matches no possible
           encrypted value (it adds a ´!´ at the beginning of the password).

           Note that this does not disable the account. The user may still be
           able to login using another authentication token (e.g. an SSH key).
           To disable the account, administrators should use usermod
           --expiredate 1 (this set the account's expire date to Jan 2, 1970).

           Users with a locked password are not allowed to change their
           password.