Add option to clear (for unity) product from port buffer storage

I have removed a contract from one port.
I cannot use the port for other purposes - the exported product is stuck in the buffer storage.
There is too little of this product for the machines to take it for storage.
I want to remove it for unity, as in the case of storages or transporters.
At this point, I will have to completely remove the buffer storage and build it again... Or enable global partial loading of trucks.