Open the Chat 💬 tab in the team window. Here you can send messages, request and send lives, and read notifications when a player joins or leaves your team.
You cannot delete your own messages in the chat, but you can delete someone else's message by clicking on the "Report and delete" button. To do so, just click the message you want to delete ✏️
❗ The message is only deleted for you. If three or more players report the same message, it is deleted for all the players in the chat 🙂