Can't shred encrypted Writer file

[SKE]

I tried to use the SHRED command in Linux to destroy an encrypted Writer file, but I got this message:

 Document file 'xxx.odt' is locked for editing by:
 Unknown User
 Open document read-only or open a copy of the document for editing.

The file seems to have set itself for read-only; I don’t remember doing it.

How do I get rid of the read-only restriction so I can shred the file?

[mikekaganski]

Actually the message you cite looks like what is shown by opening the file, instead of shredding it. I’d expect that LibreOffice itself show this when opening a read-only or blocked file.

[jbfaure]

Right click on the file in your file explorer, then choose Properties, then Permissions

Works with Nautilus in Gnome, you should have something like that in KDE or Xfce.