I had the same problem, but when I swapped the sim card for another one, then changed back they were gone. So that's one way, but I'm sure there's a proper way to delete.
Sorry if this may sound a stupid question, but where is the Logs app?
Hes talking about your caller LOG apps in the main menu....
Goto it.....then click right on the joystick....this gives you a list of all communications from the 7650!! (You can also setup filters to filter what to keep in the logs!!!)