The order delivery is handled by the delivery staff which is managed by their respective restaurant owners (merchants).

Therefore in default Yo!Yumm system, admin cannot manage order deliveries. 

However, we can make customizations in the system, if your business model requires delivery management to be handled by website admin, like in case of Swiggy and Zomato. 
Click here to enquire about the cost of customization in Yo!Yumm.