Hi,
The way to reverse the payment request are slight different depending on where they are created (IHC, TRM or Bank accounting). Here below is how to reverse payment request from TRM.
FBRA to reverse the payment document
F8BW to reverse the payment request - here you enter the payment document number you have just reversed in FBRA.
Please let me know if this applies to you or you are referring to a different type of payment request.
Taro