exclude purchase & full refund transaction

The vendor refund process may be time-consuming for you. But I'm here to share with you the steps to exclude your purchase and full refund transactions, @mikelu9661. 

I'd suggest creating a journal entry to help you save time entering three transactions. This way, you'll be able to exclude both the purchase debit and refund credit transactions. With this, you'll need the assistance of your accountant. They can determine the correct accounts you'll need to use when creating the journal entry. This is to ensure your books are accurate. Once confirmed, make sure to switch from Business view to Accountant view before performing the steps below. 

1. Go to the + New button from the left menu. 
2. Select Journal entry under Other. 
3. Set the Journal date. 
4. Fill out the necessary fields. 
5. Click Save.

View the screenshot below to show you the last three steps. For the detailed instructions, check out this article: Creating A Journal Entry in QuickBooks Online (QBO). 

Moreover, you can go to the Vendors page from the Expenses menu. This lets you manage your vendor transactions to ensure their balances are up to date. For more information, visit this article: Vendors Overview. 

I'm just a comment away if there's anything else you need. Have a great day, @mikelu9661.

How bad would it be, or I guess what are the conflicts & problems if I just exclude purchase/refund of a transaction whole without doing anything else?

Thank you for getting back here in the Community, @mikelu9661.

There will no conflicts or problems that you will encounter even if you will do nothing after you exclude purchase/refund transactions since it will not affect your balance for it is only an offset transaction.

However, if this transaction will show in your bank statement moving forward, it may inflict confusion on you since you have not recorded all activities in QuickBooks.

To know more information about vendors, you can check out this article: Vendors overview.

If you need anything else, don't hesitate to comment below. I'd be glad to assist you right away. Take care and keep safe.