Office 365 (Outlook Client for Windows) - Delete a Message
Delete messages you no longer need or want to see in your Inbox or mail folders. There are several ways you can delete a message.
Option 1: In the message list, when you point to or select a message, a trash bin icon will appear. Click on the trash icon to delete the message.
Option 2: Select the message and then press the Delete key on your keyboard.
Option 3: Select a message from the message list or open the message in its own window and select the Delete option in the ribbon.
When a message is deleted in Outlook, it’s moved to the Deleted Items folder.
Wait! I changed my mind!
If the message you want to keep is still in the Deleted Items folder, drag the message from the Deleted Items folder to another folder. When the Deleted Items folder is emptied the message is permanently gone.