Well, the thing is, those lines with second and third names have to be deleted from the file at all. The problem here is that the task is to delete all such lines using just one command. If it were not this strict I could use dd command in vi editor to do it.
By the way, the file must be edited in vi editor. So, apparently, there should some command to perform this task. That's why I asked.
Thank you, blowtorch, for the message.