Kafka 0.11.0.0 (Confluent 3.3.0) added support to manipulate offsets for a consumer group via cli `kafka-consumer-groups` command.

1. List the topics to which the group is subscribed
```bash
kafka-consumer-groups --bootstrap-server <kafkahost:port> --group <group_id> --describe
```
Note the values under "CURRENT-OFFSET" and "LOG-END-OFFSET". "CURRENT-OFFSET" is the offset where this consumer group is currently at in each of the partitions.

2. Reset the consumer offset for a topic (preview)
```bash
kafka-consumer-groups --bootstrap-server <kafkahost:port> --group <group_id> --topic <topic_name> --reset-offsets --to-earliest
```
This will print the expected result of the reset, but not actually run it.

3. Reset the consumer offset for a topic (execute)
```bash
kafka-consumer-groups --bootstrap-server <kafkahost:port> --group <group_id> --topic <topic_name> --reset-offsets --to-earliest --execute
```
This will execute the reset and reset the consumer group offset for the specified topic back to 0.

4. Repeat 1 to check if the reset is successful

### Note
* The consumer group must have no running instance when performing the reset. Otherwise the reset will be rejected.
* There are many other resetting options, run `kafka-consumer-groups` for details
  * --shift-by <positive_or_negative_integer>
  * --to-current
  * --to-latest
  * --to-offset <offset_integer>
  * --to-datetime <datetime_string>
  * --by-duration <duration_string>
* The command also provides an option to reset offsets for all topics the consumer group subscribes to: `--all-topics`