The chat profanity filter is off by default and must be enabled. At this time, the profanity filter is available for English, Spanish and French terms. If someone uses inappropriate words in the chat those words are filtered out and replaced with a series of stars.
Create the session in Collaborate. See → How can I create a custom session in Blackboard Collaborate?
Edit the Session Settings.
Scroll down to the Profanity Filter section.
Check the box for Hide profanity in chat messages.