How do I delete previously recorded tracks?

Swipe the item to the left and a Delete option will appear.

It just says “Locating…” what does that mean?

This means the app has not yet found a reliable GPS position. This usually only appears for a couple of seconds as GPS initializes, but if you dont have clear line of site to the sky and there is no other method to get a reliable location such as cell towers and wifi then you may see this until a GPS position can be established. It may also happen if you deny the app access to your location via privacy settings.