Thanks for joining this forum, @Chester_Kay. I'm here to share a few insights about how QuickBooks clear old transactions from accounts receivable (A/R). 

Ideally, you'll need to record a refund to your customer using Cheque expense. In your case, since your customers are not eligible for a refund,  you'll need to create a journal entry. Then, set the journal entry to reverse so it will offset the credits. Here's how:

Create a journal entry for Accounts Receivable

1. Go to the Plus(+) icon at the top right.
2. Under Other, select Journal Entry.
3. Select the Journal Date. Make sure to enter the date of the end of the time period.
4. Select the account affected by the invoice from the drop-down list in the Account column.
5. Enter the amount in the Debit column.
6. Enter the reason for this journal entry in the Memo field.
7. Select Accounts Receivable from the Accounts drop-down list. The amount will be entered automatically in the Credits column. 
8. Select the customer from the drop-down list in the Name field.
9. Click Save and close.

Set the journal entry to reverse

1. Click the Search icon in the upper right. 
2. Find the journal entry you created and click to open it.
3. Choose Reverse.
4. Edit the Journal Date to one day after the original journal entry's Journal Date.
5. Click Save and Close.

To ensure your books are accurate, I'd highly recommend you speak with your accountant. He/She should be able to provide you more expert ways of handling this situation.

Let me know if you have any other questions. We're always glad to assist. Take care.