How to Free up Mailbox Space by Purging Deleted Items

Outlook 2016/2019

1. Right click on your deleted items folder. A content menu will appear. Select empty folder. A message will appear informing you that everything in the folder will be deleted.  Select yes.
                        
2. Next in Outlook select the folder tab and click on Recover Deleted Items.
   
    
3. After you select Recover Deleted Items a new menu will appear. Select the following:                  Purge selected items and select all the click OK.  

OWA Web Mail

1. Just right click on Deleted Items folder and select empty and then click OK