[Spirit]

Store-bought or home-made by someone?

Store-bought - uses a hardener in their icing - you should be able to take a toothpick and lift up on the edges of the writing and pull it off. Chances are though, that the coloring used in the text-icing bled onto the layer-icing. If that is the case, there is not much you can do unless you have some wax paper.

If you do, then take a butter knife and gently "stir" (using the flat of the knife, not the tip) up the icing where the writing was. Then cut a small square out of the wax paper and lay it over a section of the icing and smooth it back out with your finger tip. A few drops of water on the icing will help to loosen it up to make it easier to work with.

Home-made - just scrape it off and blame it on a bad cook.