It is not possible to delete topic as --delete command is not available:
~/kafka_2.10-0.8.1.1/bin# ./kafka-run-class.sh kafka.admin.TopicCommand
Command must include exactly one action: --list, --describe, --create or --alter
--alter Alter the configuration for the topic.
--config <name=value> A topic configuration override for the
topic being created or altered.
--create Create a new topic.
--deleteConfig <name> A topic configuration override to be
removed for an existing topic
--describe List details for the given topics.
--help Print usage information.
--list List all available topics.
--partitions <Integer: # of partitions> The number of partitions for the topic
being created or altered (WARNING:
If partitions are increased for a
topic that has a key, the partition
logic or ordering of the messages
will be affected
--replica-assignment A list of manual partition-to-broker
<broker_id_for_part1_replica1 : assignments for the topic being
broker_id_for_part1_replica2 , created or altered.
broker_id_for_part2_replica2 , ...>
--replication-factor <Integer: The replication factor for each
replication factor> partition in the topic being created.
--topic <topic> The topic to be create, alter or
describe. Can also accept a regular
expression except for --create option
--topics-with-overrides if set when describing topics, only
show topics that have overridden
--unavailable-partitions if set when describing topics, only
show partitions whose leader is not
--under-replicated-partitions if set when describing topics, only
show under replicated partitions
--zookeeper <urls> REQUIRED: The connection string for
the zookeeper connection in the form
host:port. Multiple URLS can be
given to allow fail-over.