Deleting is not possible by default, but there is an update available that enables a delete feature.
To delete a preset, do shift+save and hold it for a second, the lights will flash and the preset is deleted. So press quickly to save, press and hold to delete. After delete it will recall the next preset/sequence in the list. To do the update:
Download this file and unzip. Inside is ‘mother.pd’ and ‘lib’
connect the synth to the computer and do the disk mode thing (C#,D#,F# + shift)
when the drive appears, go to the ‘pd’ folder. Drag the new ‘mother.pd’ and ‘lib’ into the folder to replace the old ones. Click ‘replace’ if it asks.
Eject the drive, and then just turn the synth off, then back on again, and should be good to go
Also, when you attach the PP201 using disk mode, you can backup the “Presets” folder by copying it to your computer. You can also add / delete presets from the folder. They are recalled in alphabetical order.