Entity Framework does not support batch modifications, that is, UPDATEs or DELETEs of several entities at once. Neither classic nor Code First, not even Entity-SQL.
For UPDATEs, you have to load each entity and modify it to your liking and then save changes.
For DELETEs, you don’t need to load an entity, just call Remove with a proxy entity with an assigned primary key property, like this:
Other alternatives exist: