Connect to Bash cmd line in docker:

docker exec -it addon_a0d7b954_influxdb bash

Run influx client with credentials:

influx -username homeassistant -password <password>

Go to explore and query for the following:
SHOW MEASUREMENTS ON "<db_name> eg: homeassistant"
SHOW TAG KEYS ON "<db_name>" FROM "<measurement_name> eg: °C"
SELECT * FROM "homeassistant"."autogen"."°C" WHERE "entity_id" = 'emoncms_temp_air_out'

Query template with date:
USE "<db_name>"; DELETE FROM "<measurement_name>" WHERE "<tag>" = 'tag_id' AND time < '2021-05-15'

Actual query:

USE "homeassistant"

DELETE FROM "°C" WHERE "entity_id" = 'emoncms_temp_air_out'

DELETE FROM "°C" WHERE "entity_id" = 'emoncms_temp_air_out' AND time = 1647487794071609000