BlackBerry Messenger (BBM) is a standard feature on all BlackBerry phones. If you know other BlackBerry users, you can exchange BBM pins and instant message each other. When you want to delete an instant message chat session, you can do so by clearing your BBM messages for that particular contact. Clearing a BBM chat is relatively simple, and can be done without much effort.
Launch the BlackBerry Messenger application on your BlackBerry phone.