The following buttons do not relate to the song number and must be pressed regardless of what song number (1, 2, 3, 4 or 5) is being erased.
1) Press and hold the track [6/A] button.
2) While holding down the track [6/A] button press and hold the track  button for longer then a second.
3) When prompted, press the [YES] button on the number pad twice.
You can also erase the songs as follows:
Hold down the highest white key while turning on the power. Any recorded user songs will be lost as well as any saved user registrations.
Do you need an additional help?