Yes. Follow these steps to edit a sample.

1. In Program, select your instrument you wish to edit.
2. Press Edit, and press the Keymap softkey (if you don't see it, use More > to find it).
3. Press Edit again, abdgo to Sample on the screen by pressing down arrow,
4. Press Edit once again, and now you can edit the waveform, start & end points, and loop start and end points. There also some various DSP functions you can perform here.