The easiest way how you can convert various song or multimedia playlists files (such as .m3u8 or .m3u) is to load them up in some media player and save them to whatever format suits you.
The free and highly popular VLC player is an excellent choice for some basic playlist conversions, as a lot users already use it already as default media player and have it installed on their computers, it's the most convenient way to achieve m3u8 to m3u conversion.