In the case of a security breach disclosure, it's crucial to follow proper protocol to handle sensitive information responsibly:
* Ignore the messages: Not appropriate as it disregards the potential impact and severity of the breach.
* Remove the colleague and ask members to delete the messages: While it might limit the spread of the information, it doesn't address the breach reporting requirement.
* Message the colleague privately: Might help in immediate removal of messages but does not follow the proper chain of command and reporting protocols.
* Contact the supervisor: The correct action, as it ensures that the incident is handled by higher authorities who can take appropriate measures. Reporting with screenshots ensures that there is evidence of the disclosure.
Reference: CompTIA A+ Exam Objectives [220-1102] - 2.7: Given a scenario, use proper communication techniques and professionalism.