I can completely understand a staff member who has stepped down or been demoted wanting to keep it private, so sure, don't include whether it was a demotion or resignation and why it happened, just put something like this:
Recent Staff Departures
Person has left the team.
Other person has left the team.
Thank you to both person and other person for your hard work as a staff member.
It keeps it positive for a demotion/resignation section and doesn't give away too much information that resigning/demoted staff member wouldn't want to get out there, but enough for a player to know that the player is no longer staff.
