You can revert any Manufacturing Order from "Done" status back to "Not Started" or "Work in progress". That will also revert the stock movements related to the MO (i.e. ingredients are added back to stock and the product removed from stock).

If you are tracking batches for the product, then the selected batch will remain assigned to the Manufacturing Order.

The completed products are removed from the batch, but the batch number will remain assigned to the MO. The batch itself will not be removed, even when the stock quantity in the batch is 0.

When you complete the MO once again, you do not need to re-assign the batch number as the batch info will remain attached to the MO.