I have never been able to remove one of those. Maybe someone here has or you could post in the Radicon section at TFW for assistance.

Also note that it has been repeatedly proven that 1987 toys don't react well to Hydrogen peroxide. Something else to note is that if the plastic was originally prone to yellowing, even if you restore it with the Peroxide there is nothing stopping it from yellowing again since it is the same plastic.