How to stop messages from piling up in msg_store_persistent in mnesia folder?

Question

We are using Rabbitmq.Masstransit in our application to consume the message from rabbitmq. I am receiving the acknowledgement (shown as green line) in graph. And there are no messages left in the queue as well. I have also set up TTL for the messages. So after 2 mins it gets removed from the queue in the chart of RabbitMQ management console. I can also see that a message is getting entered whenever a message gets delivered, published and acknowledged. So totally 3 messages are enetered in .rdq file. But, even after successfully receiving the acknowledgement, the entries are not getting removed from the .rdq files in msg_store_persistent and hence the folder size is increasing rapidly in the production environment. What are we missing? How can we fix this issue without having to manually delete the rdq files? We are using RabbitMQ v3.8.2 with Erlang v22.1 and massTransit v5.5.6.0

I expected the entry in rdq file to get deleted after receiving the acknowledgement. However, that is not the case. Also, the count of messages in the queue in the RabbitMQ Management Console also becomes 0 after receiving the acknowledgement. I tried setting TTL for the message. No matter what I am not able to get the entries removed in rdq file.