To delete an item you received

Click Mailbox in the Folder List.

or

To delete an item you've moved to a folder, click the folder in the Folder List.

or

To delete an appointment, task, or note you've already accepted, click Calendar in the Folder List.
Select the item, then click Delete at the top of the Item List.

or

Click the item to open it, then click Delete.

The item is removed from your Mailbox or Calendar and placed in the Trash folder. The status of the item is also updated in the sender's Mailbox or Calendar to show you've deleted the item. As long as the item remains in your Trash, you can undelete it.