When the Messenger of Allah (may Allah's peace and blessings be upon him) took a ritual bath to remove Janābah, he would start by washing his hands. Then he would pour water with his right hand over his left hand to wash his private parts. Then he would make ablution like that he would make for his prayer

‘Ā'ishah (may Allah be pleased with her) describes how the Prophet (may Allah's peace and blessings be upon him) took a ritual bath. He would start with his hands, when he wanted to wash from Janābah. He would clean his hands first because he would scoop water with them. Then he would make an ablution typical of his regular ablution for prayer. Since the Prophet (may Allah's peace and blessings be upon him) had thick hair, he would run his fingers through it with water. When water reached the roots of the hair, he would pour water over his head three times. Then he would wash the rest of his body. He would finally wash his feet.