The rule for delivery my customer orders is completely different of date of order confirmation. 

I have customers who order the last ones but are the first to be delivered and invoiced. 

Also I need to confirm SO so I need to send PO to supplier based on PO, there is no forecast.

So I want to know if there is any system to cancell automatic reservation, I would like to do it manually..  

I would like to ask too the way, by the moment to cancell reservations, it is from Sales but I can't find how to arrive.