You can only edit style tracks that you have recorded, i.e. played in.

You can edit the RHY1 and RHY2 but that's all.

I find creating styles from scratch very time consuming with Yamaha's Style Creator, and I prefer to use Style Assembly and make up a new(er) style from component parts.

Roland does style creating/editing very elegantly( I haven't been able to try a Korg), and Yamaha could take a few lessons from them.

It's probably the one area on Yamaha arrangers(well, perhaps the harmonizer) that could do with some updating and/or simplification.