Hello @jacpad,
You have the option to delete your sales transactions by excluding them. Let me show you how.
- Go to Transactions.
- Put a checkmark on all of your duplicate sales transactions.
- Select Exclude.
- Click Apply.
In the same manner, here's an article you can read to learn more about how you can handle duplicate transactions: Handle duplicate transactions in QuickBooks Self-Employed.
On top of that, I've also included this reference for a compilation of articles you can use while working with us: Banking for QuickBooks Self-Employed.
If there's anything else that I can help you with, please let me know in the comments below. I'll b here to lend a hand.