How can free up /var on logstash server

My logstash path on /var is full so logstash service cannot start . Now want to know How can free up /var on log server ? Do I have to remove file manually from /var/log or have to do free up by elastic GUI ?

I think don't think there is a way to remove logstash log files via Kibana/Elastic GUI, so you need to remove the unwanted log files manually.