How to unassign PHA4 DocumentLine of SubProject in SDK

Hi,

I am currently facing an issue updating the correct stageid of AP Invoice because it is already assign to a project.

Error Message: [PHA4.DOCNUM][line: 7] , 'Cannot proceed; A/P Invoices 0 has already been assigned to a project.'

is there a way to remove the assign stage in AP Invoice so i can re-assign to correct one?