Deletes water intake for the specified APIUser starting from the most recent entry of the day.
If a timestamp is provided, the operation is scoped to that day up to that time. If not provided, it defaults to today from 00:00:00 to the current localized time of the user.
If the quantity to delete exceeds the most recent intake, earlier intakes are also affected until the requested amount is reached.
If the quantity to delete exceeds the total water logged for the day, all water intakes for that day are deleted and the response reports how much could not be deleted.
When a partial deletion is needed (i.e. the last affected intake has more water than the remaining quantity to delete), that intake is edited rather than fully removed.
Quantity defaults to 250ml if not provided.