comment: >
  
  Won't that remove the texture of the plastic underneath and leave a shiny spot?
context: Just rest your palm there for a couple of years, worked for me >
  
  Maybe with an eraser >
  
  Eraser worked on my k630 (black writing on white board). >
  
  Try isopropyl alcohol or a simple pencil eraser. One of the two or combination of both should work. >
  
  And etch some of the plastic too >
  
  Others are offering best-guess suggestions, but here's the real answer:
  Melamine foam sponge.  Magic Eraser is the common brand.  It's an abrasive cleaning tool usually used for removing stubborn grime.  But it's perfect for this; I've done it on four different Royal Kludge boards.  Just use it dry, and rub back and forth for about 10 minutes.  It'll seem like nothing is happening at first, but be patient.