Not having any experience with this, I wouldn't know how to remove the rubber. But I am wondering why it needs to be removed?
All the circuits I have seen are covered in them. Even when the course is changed, the old marks are left there and new ones form.
Also, I would have thought they increase the tyre grip - rubber on rubber.
If he says that they must be removed, then the first thing you need to know is the what the surface is made of - concrete, wood etc. This will help determine any chemical requirements. Then you might need to consider the complete removal of the chemicals themselves for H&S reasons (for example, spray in wet conditions) as well as the possibility them affecting the tyres in future races.
Definately an interesting one...