Once the ashes are immersed in the Sangam:
Urn (Kalash): Traditionally, the earthen pot (if used) is also gently immersed or broken and immersed in the river. If it’s a metal urn, it’s usually washed in the holy water and taken back, perhaps to be reused for auspicious purposes or kept safely. Consult your Pandit or follow family custom. Do not discard it improperly.
Cloth: The cloth used to wrap the urn is typically washed in the Sangam water and then can be disposed of respectfully (some immerse it, others discard it cleanly on the banks, following local guidelines). Avoid leaving it to pollute the area. The Pandit can guide the appropriate action.