I have a MZ-R700. Are you talking about the Remote? I haven't figured how to use that to its full extent.

On the unit, while it is playing the specific track you want to delete

1 - I press [Enter] until, the word Edit shows up.
2 - Then press [Enter]. It should show Name(if you want to enter a name for the track)
3 - Then press the [>> (Fast Forward)] until Erase shows up.
4 - Then Press [Enter], where it will ask if it is OK to erase.
5 - If it is, press [Enter].

If at any time you decide NOT to proceed, press the [Stop].