Single API design approach in Java

One of our web application has multiple API's created using Facade design pattern as of now. The present design is pretty much messed-up and we are working on single design API approach. We have Delivery Services which in turn is implemented for CardsDeliveryServicesAPI, OnlineDeliverySerivicesAPI, OfflineDeliveryServicesAPI etc.. to name a few.. Basically we have few API's which are kind of redundant. We wanted to have a single generic API which can process based on the type of incoming requests. Need to know which design pattern in java can be used in this case? Any pointers in this regard would be really helpful.