Apache OpenOffice (AOO) Bugzilla – Issue 103352
removing password by resaving the file
Last modified: 2013-01-29 21:52:11 UTC
if you want to re-save a password protected file without the previously set password and you try it to do through saving the file with the same name (File - save as) only by unchecking the mark "Save with password" OOo will not do it. The old value of the password is still saved in the document. So if you need to remove the password you have also to change the name of the file. The same occur in Writer.
This is a known issue. AFAIR OOo can't distinguish a save-as overwrite with the same name from a simple save via Ctrl-S.