The account, the conversations, and everything the four know about you. All of it, permanently.
A quick confirmation, because this cannot be undone and we would rather be careful than fast.
Messages, call transcripts, everything they had learned about you, and the account itself.
If you have paid us, the law requires we keep basic billing records. That is an amount and a date. It contains nothing you ever said to any of them.
Stopping the messages is reversible and deleting is not. If you mainly want it to go quiet, stop is the one you want. And if you would like to read everything first, ask for a copy before you delete.