One thing I neglected to mention is that with the problems you've reported, you must run mc as root user.
So give the command "sudo mc" and navigate to the file you need to delete and delete the file.
You could also investigate the ownership of the file and use mc's chmod menu to change the file owner to your user account, then the Mate file manager will delete the file for you. You have to be running mc (midnight commander) under sudo or as user root to do this or it will fail.
Best regards,
David