"Outlook is synchronizing local changes made to items in this folder. You cannot remove this folder until the synchronization with the server is complete."Answer:
1. Open up Internet Explorer.
2. Log in to the Outlook Office Web Access the link is usually look like this "https://mail.[yourcompany].co.uk/owa".
3. The link will bring up a log in screen ask you, your username and password.
4. Check the "Deleted Items" on the left hand side menu panel of where the Inbox, sent and other folders are.
5. Expand the "Deleted Items" folder and you should be able to see those folders you always wanted to get rid.
6. To delete them folders and simply right click on the folder and click "Delete.
7. Your outlook program should synced with the server and now the folders are in the "Deleted Items" have gone forever!