Thanks for joining the thread @Mia2,

For deleting transaction in QuickBooks for Mac you can follow the steps which my colleague AlexV provided by clicking the transaction and press the Delete button on your keyboard. Also, you can use the shortcut key on your keyboard by pressing the "Command + D" to delete the transactions

To learn more about tracking sales and income, bills and expenses, inventory, invoices, and many more visit this article: QuickBooks Desktop for Mac Help Article.

If you need further assistance feel free to leave a comment below. I'll be happier to help. Have a good one!