I have issued the command to delete a topic:
./bin/kafka-topics.sh --zookeeper localhost:2181 --delete --topic vip_ips_alerts
It seemed to
The deletion happened for me almost immediately (v 0.9). I believe that it should be the same for you.
Once marked, the deletion will be triggered on the kafka node which is the topic partition leader. The thing to remember is that the the topic partition leader must be configured correctly (in terms of listeners), otherwise it will not receive the instruction to delete the logs.
I had my "marked for deletion" topics stuck at that state until I corrected my server properties and restarted the respective node.