Is anyone able to tell me how to delete a presentation in the employee channel?  the error message I keep getting is that it is referred to somewhere else in Odoo but I have not made reference to it anywhere else.  I uploaded 2 pdf documents under presentations into the employee Channel as a test and now I cannot delete either of them.  I went into Slides to try to delete but could not, so I archived them instead but they are still showing in the employee channel.  I am using Odoo Version 11.   Thanks in advance.