I use a third party application to manage Contacts on my iOS and macOS devices. However, I suspect the majority of Mac and iOS people just use the Contacts App supplied with the specific operating system. If this is you, then read this article for information on how to Delete Contacts on all of these devices. It is not a difficult procedure, but Deleting Contacts is a little different on each device. It really is not a bad idea to do a little cleanup on our Contacts occasionally.