DELETE
FROM xf_conversation_message
WHERE conversation_id IN (
SELECT conversation_id
FROM xf_conversation_master
WHERE user_id = 2
);
DELETE
FROM xf_conversation_recipient
WHERE conversation_id IN (
SELECT conversation_id
FROM xf_conversation_master
WHERE user_id = 2
);
DELETE
FROM xf_conversation_user
WHERE conversation_id IN (
SELECT conversation_id
FROM xf_conversation_master
WHERE user_id = 2
);
DELETE
FROM xf_conversation_master
WHERE user_id = 2;