When the voucher is shown on the screen, press the DELETE button (GOLD <F1> key followed by the D key). The upper half of the voucher is deleted from the record system and the screen drops to the lower half of the screen.
QUERY the individual detail lines and while each individual detail line is shown, press the DELETE button (GOLD <F1> key followed by the D key). Upon doing so the detail line is deleted from the record system. This step must be done for each detail line. Leaving the screen is impossible until the detail lines are deleted.