To delete a document, go to the upper menu, File and choose Open. Locate the document you would like to delete, select it and click the 'Delete' button at the top of the window. Note that the document will still be available in the Recently deleted folder in the account from where the document was deleted.
See here pre-1.28 version view
Since version 1.26 you can also do it from Analytics tab through Documents:
See here pre-1.28 version view
