I Am configuring an installation of Odoo 10 , I'm done testing the Payroll module...  I just discovered that i can't delete the test payslips  or reset them to draft. When I click refund, it generates more accounting entries in addition to the original payslip payable. 

How can I reset a payslip to draft after the status is done? Or yet...  How can I completely delete a payslip from the system