try this:

turn on document locking on the database

have someone with manager access to the database open a view in the db. right click on the locked document.

you should see the option 'unlock document' listed - click it

turn off document locking. that should work

note that a document is 'locked' by having the fields $Writers and $WritersDate present - if they are there, Notes will treat the document as locked. if the above technique does not work, any other technique to delete those fields will unlock it.