[Enhance] Self account delete

- Add support for users destroy their own accounts

latest version/web/system.py

@@ -261,12 +261,3 @@ def ban_one_user(c, user_id):
               {'a': user_id})
     c.execute('''delete from login where user_id=:a''', {'a': user_id})
     return
-
-
-def clear_user_score(c, user_id):
-    # 清除用户所有成绩，包括best_score和recent30，以及recent数据，但不包括云端存档
-    c.execute('''update user set rating_ptt=0, song_id='', difficulty=0, score=0, shiny_perfect_count=0, perfect_count=0, near_count=0, miss_count=0, health=0, time_played=0, rating=0, world_rank_score=0 where user_id=:a''',
-              {'a': user_id})
-    c.execute('''delete from best_score where user_id=:a''', {'a': user_id})
-    c.execute('''delete from recent30 where user_id=:a''', {'a': user_id})
-    return