--------------
DELETE AHR FROM app_highest_record AHR
JOIN (
  SELECT AppHighestRecordID FROM (
    SELECT AppHighestRecordID,
           ROW_NUMBER() OVER (
             PARTITION BY MaestroID, PlayerID, AppID
             ORDER BY CASE WHEN AppID = 105 THEN HighestRecord ELSE -HighestRecord END,
                      AppHighestRecordID DESC
           ) AS rn
    FROM app_highest_record
  ) ranked
  WHERE rn > 1
) dup ON dup.AppHighestRecordID = AHR.AppHighestRecordID
--------------

Query OK, 8795 rows affected (0.942 sec)

--------------
SELECT 'app_highest_record' AS table_name,
       COUNT(*) AS total_rows,
       COUNT(DISTINCT MaestroID, PlayerID, AppID) AS unique_combos
FROM app_highest_record
--------------

+--------------------+------------+---------------+
| table_name         | total_rows | unique_combos |
+--------------------+------------+---------------+
| app_highest_record |     220648 |        220648 |
+--------------------+------------+---------------+
1 row in set (0.190 sec)

--------------
SELECT 'typing_exam_highest_record' AS table_name,
       COUNT(*) AS total_rows,
       COUNT(DISTINCT MaestroID, PlayerID, WritingID) AS unique_combos
FROM typing_exam_highest_record
--------------

+----------------------------+------------+---------------+
| table_name                 | total_rows | unique_combos |
+----------------------------+------------+---------------+
| typing_exam_highest_record |      20413 |         20413 |
+----------------------------+------------+---------------+
1 row in set (0.024 sec)

Bye