Can't delete documents

I created several sample categories and several sample documents before uploading in earnest.
I can't delete the documents that I created.
I'm logged in as a super user and super users have permission to delete documents.
I also can't delete the last category. Was able to delete the others. (Could it be that you are required to have at least one category?)
Help!

Dear Karen

The issue you mentioned is strange. As a super users, you should be able to delete everything you want. In this case, please submit a support ticket sending me administrator and FTP account of your site.

I will check and solve the issue for you.

Regards,

Tuan

I have the same problem! is there any solution meanwhile?
regards,
dagmar