Hi, I hope this response isn't too late to help you...
The impression that I got from your description was that the white writing is screen printed onto the surface.
If this is the case, the letters will feel raised above the surface if you run your fingernail over them.
If they are indeed screen printed, it's pretty easy to remove without marring the surface.
Anodizing is pretty hard, but if you try to use sandpaper to take the lettering off, you may damage the anodized surface.
This is because most abrasives are as hard or harder than the anodized layer, in fact a lot of abrasives are made of Aluminum Oxide, the same thing as an anodized surface...
The method I've had most success with is to use a knife blade to gently scrape away the screen print.
Try to slide the knife edge so that it hits the edge of the lettering.
If you're careful, you'll be able to chip away the painted letters without marring the finish whatsoever.
Of course, if the letters are recessed this won't work...