I'm here to help you un-split transactions in QuickBooks Self-Employed (QBSE), emelie.
To remove the split option for transactions and prevent them from being split in QuickBooks Self-Employed, you can follow the steps below:
- Navigate to Transactions and locate the transaction you want to un-split.
- Click the Split icon.
- Within the Split transaction window, choose the Trash can icon next to the category you wish to eliminate.

- Click on Save.
You can check out this article for more detailed steps: Split and Exclude Transactions.
You can also check these articles for future references:
Keep your posts coming if you need further assistance un-splitting transactions in QBSE. I'm always here to help. Have a good one.