This took only 10 seconds. So this will be used to remove the old entries, but I will schedule a maintenance job to END CONVERSATION any extra entries that...

I have come across other ideas, most of which require the DB being in single user mode

ALTER DATABASE TestDB

SET DISABLE_BROKER

ALTER DATABASE TestDB

SET ENABLE_BROKER

ALTER DATABASE TestDB WITH ERROR_BROKER_CONVERSATIONS

ALTER DATABASE TestDB

SET...