Hamsters keep themselves clean using sand, which should always be in the enclosure. Bathing your hamster with water and, worse, using shampoo - is life-treatening.
You should never use water and shampoo to wash your hamster. Even if the shampoo is "hamster-safe" - no rodent should be exposed to water and soap!
Recommended sand is hamster sand and soft dust-free reptile sand. I included a comparison of how it should and shouldn't look like. Keep it in your hamster's enclosure at all times. A large bowl you can find at your kitchen could work. It gets heavy, so always sand on a platform.
Please avoid sand with large particles, and dusty sand. It is very hard to find low-dust chinchilla sand that's why I recommend avoiding it.
Not all countries have hamster or reptile sand, so you can try children's play sand!
