How to do simple edits on Panasonic DMR-E50

Just got a DMR-E50, have some shows and movies I recoreded on it using -R disks but have not finalized them yet. On most of the recordings I have a minute or two of other program material at the front and rear of the recording that is not related to the show or movie because I started the recored a little quick and did not shut if off at the end on time. Is there an easy and simple way to erase the unwanted portions???