For the Statement of Cash Flow, when determining the purchases of inventory made and then the amount of cash paid to creditors for inventory, when there is purchase returns how is this recorded? (i.e. how is the purchase returns recorded in the inventory and accounts payable ledger)

I have read that if there are purchase returns that it is debited in the inventory ledger and also debited in the accounts payable- i don't understand the logic behind this. My thinking is that if it has already been removed from inventory and then the accounts payable (purchases) figure that is found at the end of doing the inventory ledger which is used in accounts payable means that it doesn't need to be removed from accounts payable.