If your ApsaraMQ for Kafka instance runs broker version 0.10.2, deleting a consumer group from the console does not stop message accumulation (consumer lag) alerts for that group.
Apache Kafka versions before 2.0 lack the AdminClient API for physically deleting consumer groups. The console deletion is only a soft delete. The consumer offset data remains in the internal topic __consumer_offsets. Because alerts are driven by consumer offsets, the alerts persist even though the group no longer appears in the console.
How to fix this
Upgrade to broker version 2.2.0 or later, then recreate the consumer group with the same configuration and delete it again. On version 2.2.0+, deletion physically removes the consumer offset data. See Upgrade the version of an instance.
Disable the message accumulation alert rules if you no longer need them. See Monitoring and alerting.
Wait for the consumer offset retention period to expire. Consumer offsets in ApsaraMQ for Kafka are stored in the internal topic __consumer_offsets and cannot be deleted directly. If the consumer offset is not updated within the retention period, it is automatically deleted. Configure the retention period under Change message configurations.
Note: If any consumer thread exists in the group, the consumer offset is not deleted even if it exceeds the consumer offset retention period. See Why consumer offset expired but has not been deleted?
Reset the consumer offset to 0. Create a new consumer group and reset the consumer offset of each partition to 0 in the console. This clears the accumulated offset data. See Reset consumer offset.
Applicable scope
ApsaraMQ for Kafka