To fully refresh the elementary_test_results table (and all other Elementary tables), effectively deleting all records and starting fresh, you should run the following dbt command with the special Elementary full refresh variable:

dbt run --select elementary --full-refresh --vars '{"elementary_full_refresh": "true"}'

This command ensures that all Elementary incremental models, including elementary_test_results, are fully refreshed and all historical data is deleted. The standard dbt --full-refresh flag alone does not affect Elementary's incremental models unless you also set the elementary_full_refresh variable to true. This approach is confirmed in multiple sources and is the recommended way to reset all Elementary tables and start with a clean slate [Elementary dbt package full refresh](https://docs.elementary-data.com/guides/modules-overview/dbt-package#package-full-refresh), [Slack discussion on full refresh](https://slack.com/archives/C02CTC89LAX/p1682944161312479), [Another Slack example](https://slack.com/archives/C02CTC89LAX/p1674823249739599). If you want to delete only specific records or reset metrics for a particular table, you can manually delete rows from the relevant Elementary tables in your database, but for a complete reset, the command above is the standard approach.