As the comments indicate your original question lacked a lot of information, your edit does provide a bit more information, however they don't really show a lot of effort from you in looking for an answer yourself.
You seem to have found the Core Service API already, and I do suggest checking out the API documentation for it in more detail (it can be downloaded here https://docs.sdl.com/LiveContent/content/en-US/SDL%20Web-v5/GUID-2301148A-E3EA-43EF-A2FC-7D3C9BAEE8FF). Once you do, you might stumble upon the
ICoreServiceBatch201501 Interface with the description:
This interface provides functionality for creating predefined Batch operation.
Looking into its methods you will find the
ICoreServiceBatch201501.BatchDelete method, which takes a list of input items. Using this method will decrease the amount of calls from the Core Service to the CM core to one, but keep in mind, deleting an item is a heavy operation, since all the references of that item need to be checked, and it will fail when the item is in use.