If you do not want a message, you can Permanently delete it with the methods below:
Method 1: Using "Shift + delete":
Step 1: Click the message you want to delete in the message window;
Step 2: Pressing "Shift" key and pressing "Delete";
Step 3: In the message warning window, click "Yes" to permanently delete the message.
Method 2: Alternatively, please use the method below:
Step 1: Select the message to be deleted, the "×" icon will appear at the end of the message. Click to delete the message;
Step 2: The message will be moved to the "Deleted Items" folder if you are using Exchange Account (e.g., school or company working outlook); or moved to the "Trash" folder if you have personal desktop Outlook;
Step 3: In the "Trash" folder, or "Deleted Items" folder if you use Exchange Account, click the message and click the "x" to delete message again to permanently delete the message.