Hi Tom and welcome on forum,
If you want to delete style from user style folder falow that instruction:
pres Disk
pres C INTERNAL if not selected
select USER STYLE Folder
select Sub folder with style who want to delete(BALAD,BALLROM etc)
pres ENTER
select Style to delete
pres User5/10 button DiSK MENU
select DELETE with F2 button
pres EXECUTE
That is all
Hope I helping you