Thank you for posting here in the Community, @Frogfeathers.
Let me share some information about deleting a customer in QuickBooks Desktop.
QuickBooks Desktop won’t allow deleting a customer if it has an open balance. If you rarely use the name of the customer. Consider making it inactive so that it doesn’t appear on the list, but the transaction will still show up.
However, If you don't need to keep historic accounts information, you can clear old transactions from your company accounts file by deleting each transaction. Deleting a transaction removes your customer completely.
To do that here’s how.
Once done, you can now delete the customer on the customer's list.
In QuickBooks Desktop, you can also delete batch transactions. If you wanted to know-how, you can use this article as your guide. Delete or void batch transactions.
Please know that I'm always here to help you if you have any other questions about deleting or making customers inactive in QuickBooks Desktop. Have a great day!