Thanks. I did see that post and tried again just now. I find the “Backups on Secure Online Storage” folder, right click and select Explore, a progress bar seems to indicate it is being opened, but it never opens to let me do anything.
In this case, you will have to contact Symantec Customer Support (you can chat for free with them at the link below); explain the situation to them and tell them that you would like to have your online storage space purged: