How can I cleanup the HiveMQ message cache dir?

Question

I found those two folders are growing up pretty fast, and it seems there is no way to clean it up.

/opt/hivemq/data/persistence/publish_payload_store


/opt/hivemq/data/persistence/retained_messages

I set message (or conn) with following attributes:

qos(MqttQos.EXACTLY_ONCE)
retain(false)
cleanStart(true)
keepAlive(60)
sessionExpiryInterval(60)

HiveMQ version : HiveMQ CE 2020.2 with MQTT5