You cannot change the point of sale's tax included flag because it has sales. You cannot delete sale "%(sale)s" because it has a number. The sale "%(sale)s" is done so cannot have an amount to pay. The sale "%(sale)s" is cancelled so cannot have amount paid. To delete payment "%(payment)s", you must reopen session "%(session)s". To delete payment "%(payment)s", you must reopen sale "%(sale)s". Each company can only have one cash payment method. Each point of sale can only have one session open. A session can be used as previous only once. To close session "%(session)s" you must change end amount to have %(amount)s instead of %(end_amount)s. To delete session "%(session)s", you must reopen it. You cannot delete transfer "%(transfer)s" because it is posted. To delete transfer "%(transfer)s", you must reopen session "%(session)s".