You can delete an email by a giving right-click on it and selecting Delete. If you are not able to delete your emails, consider the below procedure.
Open the Outlook 2016 application on the computer, click the File menu from the menu bar.
Select the Account Settings menu on the right panel in the Outlook window.
Choose Account Settings from the list of options.
In the Account Settings window, below the E-mail panel, double-click on the email address for which you have to make the settings.
Now, click the More Settings button in the Add Account window.
Navigate to the Advanced tab, then check if both the options below Deleted Items are enabled. If they are not enabled, then, tick the checkbox of both options.
Now, click OK to save the changes in the settings and then again try to delete the emails.
When you hard delete the emails, the deleted emails do not move to the Deleted Items folder. Instead, it gets permanently deleted.
To execute the hard delete, right-click the email and an Options list appears.
Press the Shift key and also click the Delete option from the list.
Release the Shift key after clicking Delete.
Run the Outlook 2016 program in the Safe mode to delete the emails. These steps help to perform the deletion of emails.
Select the Power icon on the Windows 10 desktop, then while pressing the Shift key, click the Restart option.
When the computer restarts, select Troubleshoot. Following that, choose Advanced options and then click Startup Settings. Finally, select the Restart button.
Now, you have to press the number which has the Safe Mode menu.
Next, start the Outlook application and delete the emails.