How do I remove some information on Less Common Income that I put in by mistake?

You can delete it.

Here's the general procedure for viewing the forms list and deleting unwanted forms, schedules, and worksheets in TurboTax Online:

1. Open or continue your return in TurboTax.
2. In the left menu, select Tax Tools and then Tools.
3. In the pop-up window Tool Center, choose Delete a form.
4. Select Delete next to the form/schedule/worksheet in the list and follow the instructions.