I want to delete a POS session due to the reason that I was testing order import-export feature. But this message displays "Cash control can only be applied to cash journals".

I checked in code https://github.com/odoo/odoo/blob/10.0/addons/point_of_sale/models/pos_session.py#L128

but there the function is computational. 

I am using Odoo 10, and there are 4 account.bank.statement lines:-