SQL Database:

This is more tricky, as there are dependencies that need to be deleted. I am using MySQL, and these commands work for me:

USE mlflow_db;  # the name of your database
DELETE FROM experiment_tags WHERE experiment_id=ANY(
    SELECT experiment_id FROM experiments where lifecycle_stage="deleted"
);
DELETE FROM latest_metrics WHERE run_uuid=ANY(
    SELECT run_uuid FROM runs WHERE experiment_id=ANY(
        SELECT experiment_id FROM experiments where lifecycle_stage="deleted"
    )
);
DELETE FROM metrics WHERE run_uuid=ANY(
    SELECT run_uuid FROM runs WHERE experiment_id=ANY(
        SELECT experiment_id FROM experiments where lifecycle_stage="deleted"
    )
);
DELETE FROM tags WHERE run_uuid=ANY(
    SELECT run_uuid FROM runs WHERE experiment_id=ANY(
        SELECT experiment_id FROM experiments where lifecycle_stage="deleted"
    )
);
DELETE FROM runs WHERE experiment_id=ANY(
    SELECT experiment_id FROM experiments where lifecycle_stage="deleted"
);
DELETE FROM experiments where lifecycle_stage="deleted";