Under the Stores & Channels section you have the ability to update or delete a connected store.

Updating the Store Name does not update the orders previously assigned to that store, so all existing orders will still be listed under the old name. Likewise, deleting a store or channel does not remove the old orders.

To remove these orders from your view, they should all be marked as shipped. Once marked as shipped, they are no longer viewable unless they are searched for and remarked (CSR, BackOrder, etc).