Edit your /etc/rabbitmq/rabbitmq.config
and then reload the settings from there with:
sudo rabbitmqctl eval '{ok, [C]} = file:consult("/etc/rabbitmq/rabbitmq.config"), {rabbit, R} = proplists:lookup(rabbit, C), {ssl_options, O} = proplists:lookup(ssl_options, R), application:set_env(rabbit, ssl_options, O).'