Delete message if node/entity is unflagged

Hi !
I am using the message module to log whenever a node is flagged by users. How can I delete a message when the same node is unflagged by a user?

Use Case:
- User 1 flags Node A
---> System logs message saying User 1 has flagged Node A
- User 2 flags Node A
---> System logs a new message saying User 2 has flagged Node A
- User 2 unflags Node A
---> System deletes the message that says User 1 has flagged Node A, but keeps the message for User 2. Currently, the message is not deleted for User 1

Thanks,
Lofos