Shave off hair. Perhaps a little flippant, but the only "permanent" way to get rid of lice is to shave your head. Since most of us won't do that, there are other options you can employ to make sure you don't get it back. Wash all head and hair accessories on hot, or soak in alcohol. Clean fabrics such as couches after exposure. And don't share hats! avoid trying on helmets in stores. Check hair frequently.
Baldness. Some wants to cut the hair very short to get rid of the nits or eggs of the lice permanently. They wait for the hair to grow again. Does that answer your question? Thanks.