You can delete a single Email message or multiple Email messages at a time.
To delete an Email message:
Select the Email message that you want to delete.
Click Delete on the message toolbar to delete the selected Email message.
Alternatively, right-click the Email message and select Delete from the context menu to delete the Email message.
Also, press the Delete key on your keyboard to delete the selected Email message.
To delete multiple Email messages, perform the following steps:
Press the Control key and select all the Email messages that you want to delete.
Click Delete on the message toolbar in two-pane layout.
Click Delete on the message listing toolbar in three-pane layout. Alternatively, Select the Email message and click Delete on the message toolbar in three-pane layout.
Alternatively, right-click the Email message and select Delete from the context menu.