You can delete individual documents from the index using the IClient interfaces Delete method. For example, the code below deletes a BlogPost with ID 42.
You can delete all documents that match criteria defined in a filter expression. For example, the code below deletes all documents of type BlogPost, as well as those of a type inheriting from BlogPost that are tagged with "Banana".
client.Delete<BlogPost>(x => x.Tags.Match("Banana"));