You can delete an entry from a journal voucher in SAP Business One so long as the journal voucher from which you want to delete entries has the status Open.
1) From the SAP Business One Main Menu, choose: Financials > Journal Vouchers. The Journal Vouchers window appears.
2) In the upper table of the window, choose the journal voucher from which you want to delete entries. The lower table of the window displays the entries recorded in the selected voucher.
3) In the lower table, select the row(s) for the entries you want to delete.
4) In the menu bar, choose: Data > Delete Row.
5) Choose Update.