You can give your Russian Tortoise or other Tortoise a bath by placing them in a container of water.
Then allow the Russian Tortoise to soak in the water for at least 30 minutes, then pour some warm water over the Tortoise and scrub the Tortoise with a soft bristled brush and gently scrub the Tortoise's shell.
Also make sure to brush and rinse the neck, tail and other limbs of the Tortoise.