No worries on the terminology, if you have not yet paid the voucher (have not posted a check against it yet), you can simply void the voucher to clear it out. That is available in the Payables Workbench, Accounting > Accounts Payable > Workbench. In the list of payables find the voucher in question, right click and Void Voucher. Since you mention a test database I would recommend doing it there first just so you can see the resulting GL transactions first. Afterwards you should be able to redo your voucher. If the voucher hasn't been posted yet then you can just delete it, but it sounds like it has been.