Just leave it alone. It will come off by itself if the tortoise is set up in the correct type of enclosure. Have you read our Russian tortoise care sheet?
Russian tortoises have great personalities, are very hardy, tolerate a wide variety of enclosure parameters, stay small, and are generally a good "starter" tortoise in my opinion. Here is how I like to set them up: Indoor Enclosure type and size: Most people want to know the minimum size...