You can delete the index directly but do note that this will remove all scalars from your experiments.
To delete you can use the following:
curl -XDELETE "localhost:9200/events-training_stats_scalar-d1bd92a3b039400cbafc60a7a5b1e52b"
Hi @<1579280543999070208:profile|SourFly7> , this index holds scalars of some experiments. You can reduce it by deleting some experiments. Do you have any other large scalar indices?
Here is an example for auto cleaning. Did you delete ALL experiments?