How can I process credit/refunds given to me when taking unused materials/items back to suppliers purchased from?

I can help you enter the refund in QuickBooks Online, info-djhelps-co.

You can create a supplier credit for the item that was taken back to the merchant. Here's how:

1. Click + New, then select Supplier Credit.
2. In the Supplier field, select the appropriate supplier name.
3. Enter the Payment date, Amount, and Item details (this is for the product you’re getting credit for).
4. Click Save and close.

You can then apply the credit to any open or future bill. Check out this article for instructions: Record a customer refund or supplier refund in QuickBooks Online. Proceed to Supplier refunds for outstanding bills, then Apply supplier credits to a bill.

Get back to me if there's anything else I can help you with processing refunds in QuickBooks. I'll be right here to guide you.